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LABORATORY  MANUAL  OF  PHYSICAL  GEOGRAPHY 


THE  MACMILLAN  COMPANY 

NEW  YORK   •    BOSTON   •    CHICAGO 
ATLANTA  •    SAN   FRANCISCO 

MACMILLAN  &  CO.,  Limited 

LONDON   •    BOMBAY  •    CALCUTTA 
MELBOURNE 

THE  MACMILLAN  CO.  OF  CANADA,  Ltd. 

TORONTO 


( 


A    LABORATORY   MANUAL 


OF 


PHYSICAL     GEOGRAPHY 


BY 


PROFESSOR  R.  S.  TARR  and  O.  D.  VON  ENGELN 

OF    THE    DEPARTMENT   OF    PHYSICAL   GEOGRAPHY 
AT   CORNELL    UNIVERSITY 


FOR   USE   IN   CONNECTION  WITH   A  GENERAL   COURSE   IN 

PHYSICAL   GEOGRAPHY  IN   HIGH   AND   SECONDARY 

SCHOOLS  AND  IN  COLLEGES 


OF   THE 

UNIVERSITY 

OF 


Nefo  fgotfe 
THE  MACMILLAN  COMPANY 

.1910 

All  rights  reserved 


Copyright,  1910, 
By  THE  MACMILLAN  COMPANY. 


Set  up  and  electrotyped.     Published  March,  1910. 


Nortoooo  $resa 

J.  S.  Cushing  Co.  —  Berwick  &  Smith  Co. 

Norwood,  Mass.,  U.S.A. 


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PREFACE 

The  subject  of  physical  geography,  above  all  others,  leads  to  an  appreciation  by  the  pupil 
of  the  natural  world  in  which  he  lives,  and  an  introductory  course  in  physical  geography 
should  include  specifically  a  training  in  observation  and  deduction. 

In  the  planning  and  writing  of  this  manual  these  fundamental  concepts  of  the  necessity 
of  making  the  outlines  at  once  practical  and  usable  for  the  teacher  with  only  a  limited 
laboratory  equipment,  and  at  the  same  time  offering  to  the  pupil  this  training  in  observation 
and  deduction  —  in  fact,  compelling  it  —  have  been  constantly  kept  in  mind,  and  it  will  be 
found  that  there  is  a  specific  purpose  for  each  exercise  and  that  the  groups  form  coherent 
wholes.  It  is  the  belief  of  the  authors,  moreover,  that  the  exercises  cover  the  whole  subject 
adequately,  and  that  the  order  in  which  they  are  arranged  will  be  found  the  best  for  present- 
ing the  subject.  On  both  these  points  some  teachers,  for  specific  reasons,  may  take  issue. 
This,  however,  implies  no  criticism,  either  on  the  manual  as  arranged  or  on  the  teacher; 
for,  on  the  one  hand,  the  loose-leaf  construction  of  the  manual  makes  it  a  very  simple  matter 
for  the  teacher  to  change  the  order  or  introduce  other  work ;  while  on  the  other  hand,  the 
authors  feel  that  teachers  who  are  progressive,  capable,  and  enthusiastic  over  the  subject 
should  be  given  the  greatest  latitude  in  carrying  out  their  own  ideas.  The  laboratory  study 
of  physical  geography  has  an  intense  human  interest  and  affords  the  best  possible  opportunity 
for  the  infusion  of  a  strong  teaching  personality. 

A  number  of  novel  ideas  and  methods  have  been  incorporated  in  this  manual,  but  these 
new  features  are  not  to  be  regarded  as  experiments.  The  senior  author  has  had  over  fifteen 
years'  experience  and  the  junior  author  four  in  the  laboratory  teaching  of  physical  geography, 
and  the  make-up  of  this  manual  incorporates  plans  that  have  been  successfully  used  with 
classes  after  repeated  changes  and  modifications  to  secure  the  best  possible  results. 

The  feature  which  will  first  attract  attention  is  the  leaving  of  space  after  each  question 
for  the  student  to  write  the  answer.  This  serves  a  double  purpose.  It  insures  the  student's 
following  the  argument  of  the  outline  and  the  appreciation  of  every  point  by  personal  obser- 
vation and  deduction.  The  work  thus  becomes  distinctly  laboratory  work  and  not  essay 
writing  under  the  delusion  that  laboratory  work  is  being  done.  This  latter  condition  is  the 
greatest  fault  that  the  authors  have  found  in  most  of  the  laboratory  note-books,  from  various 
schools  throughout  the  country,  which  have  come  under  their  inspection.  In  the  second 
place  this  plan  very  materially  lightens  the  labor  of  the  overworked  science  teacher  in 
inspecting  the  note-books  of  the  students.  There  is  a  place  for  every  answer  and  every 
answer  should  be  in  its  place.  Any  incompleteness  is  readily  detected,  as  is  also  the  correct- 
ness of  the  student's  interpretations.  Furthermore,  the  time  of  the  student  is  conserved  for 
the  actual  observations,  inasmuch  as  there  is  no  need  for  the  laborious  rewriting  of  questions 
in  order  to  make  the  disconnected  answers  coherent.  There  is,  however,  sufficient  space 
allowed  after  every  exercise  to  permit  of  the  insertion  of  other  material  presented  by  the 
teacher;  accordingly,  the  exercises  may  vary  considerably  in  different  localities  to  insure 
a  fuller  understanding  of  local  conditions. 

Another  feature  which  we  feel  sure  will  meet  with  general  approval  is  the  insertion  of 


201630 


all  maps,  figures,  diagrams,  and  tables  at  the  exact  place  where  they  are  needed.  The  con- 
venience of  this  plan  will  make  its  own  appeal,  and  needs  no  further  amplification  here.  ^~ 

The  pedagogical  departure  in  which  this  manual  differs  most  markedly  from  those  now 
in  use,  and  which  is  an  altogether  novel  feature  of  these  outlines,  is  the  method  of  presenting 
the  physiography  of  the  lands.  In  the  past,  in  the  authors'  own  experience  and  as  related 
by  other  teachers,  the  map  work  on  which  this  phase  of  the  subject  is  necessarily  based  has 
been  most  distasteful  and  irksome  to  the  student.     This,  we  believe,  is  due  to  two  causes : 

(1)  the  incoherent  manner  in  which  the  various  topics  have  customarily  been  treated;  and 

(2)  the  fact  that  these  topics  have  never  been  tied  on  to  any  geography  of  which  the  student 
had  a  previous  knowledge.  To  illustrate  what  is  meant,  take  the  subject  of  the  development 
of  river  valleys.  In  the  first  place  the  student  was  taught  that  Niagara  River  had  a  young 
valley,  and  he  studied  its  characteristics.  The  Mississippi,  perhaps,  was  next  studied  as  an 
old  valley.  Then  there  was  a  jump  to  the  study  of  a  volcanic  cone,  Mt.  Shasta.  Nowhere 
any  logical  development  of  the  body  of  the  subject-matter,  nor  any  relation  between  succeed- 
ing exercises. 

This  difficulty  we  believe  we  have  successfully  solved.  In  this  manual  young  rivers  are 
studied  in  connection  with  young  plains,  old  rivers  on  old  plains,  and  plains  in  turn  are  con- 
sidered in  successive  stages  in  their  cycle  of  development  from  young  to  old.  The  basis  of 
the  whole  study  is  a  series  of  carefully  selected  United  States  Geological  Survey  topographic 
maps,  and  the  position  of  these  areas  the  student  accurately  locates  on  a  United  States  map, 
on  which,  also,  he  plots  that  physiographic  division  of  the  country  which  has  conditions  simi- 
lar to  those  shown  in  detail  on  the  topographic  map  he  is  studying. 

The  results  in  our  own  classes  have  been  very  gratifying.  The  students  pursue  the  work 
with  keen  interest ;  they  gain  a  very  clear  notion  of  the  physical  geography  phenomena  which 
the  maps  illustrate;  moreover,  they  associate  the  typical  conditions  of  the  topographic  maps 
with  distinct  areas  and  regions  of  the  United  States  and  thus  gain  a  clear  comprehension 
of  the  varied  topographic  features  of  their  own  country  and  of  their  extent  and  significance. 
This  supplies  the  element  of  human  interest  which  has  been  so  lacking  in  elementary  physical 
geography  study  in  the  past;  and  it  is  largely  to  this  fact  that  the  eager  interest  of  the 
students  in  the  above  plan  of  study  may  best  be  ascribed. 

The  sections  dealing  with  mathematical  geography  and  tidal  phenomena  have  been  made 
very  simple.  These  are  complex  subjects  at  best,  and  it  is  the  belief  of  the  authors  that  they 
are  of  a  distinctly  minor  importance  in  a  course  in  elementary  physical  geography. 

Emphasis  should  be  placed  on  the  study  of  the  processes  of  erosion,  transportation,  and 
deposition  as  made  possible  by  the  use  of  the  tank  and  land  model,  or  some  modification  of  it. 
Such  work  is  of  the  greatest  value  in  enabling  the  students  to  get  a  clear,  clean-cut  concept 
of  these  processes  and  their  results ;  and  it  enables  them  to  proceed  intelligently  with  the 
study  of  the  topographic  forms  shown  on  relief  maps. 

A  few  type  excursions  are  included,  four  for  the  fall  and  three  for  the  spring.  It  is,  of 
course,  not  possible  to  write  excursion  outlines  in  detail  that  are  suitable  for  widely  different 
localities ;  hence  these  excursions  are  generalized.  It  is  the  hope  and  belief  of  the  authors 
that  they  will  be  found  useful  in  many  schools ;  but  it  is  confidently  expected  that  for  some 
or  all  of  these  many  teachers  will  substitute  specific  outlines  adapted  to  the  opportunities 
of  the  locality. 

It  is  our  belief  that  if  a  multitude  of  references  are  given,  none  will  be  used.  There- 
fore we  have  confined  ourselves  in  the  outlines  to  references  to  Tarr's  "New  Physical 
Geography."  Here  may  be  added  the  titles  of  several  publications*which  the  teacher  will  find 
valuable  for  reference :  Professional  Paper  #  60,  United  States  Geological  Survey.  List  of  the 
Publications  of  the  United  States  Geological  Survey.      These  may  be  obtained,  gratis,  on 


C 


VI 


application  to  the  Director  of  the  United  States  Geological  Survey,  Washington,  D.C.     In 

Sthe  list  of  publications  the  teacher  will  find  what  has  been  published  on  the  home  locality, 
and  should  send  for  such  papers  as  are  available.     Other  valuable  helps  are :  — 

Johnson,  Mathematical  G-eography,  American  Book  Co. 

Pirsson,  Rocks  and  Rock  Minerals,  Wiley  &  Sons. 

Davis,  Elementary  Meteorology,  Ginn  &  Co. 

Ward,  Practical  Exercises  in  Elementary  Meteorology,  Ginn  &  Co. 

Other  text-books  of  physical  geography. 

Many  valuable  papers  on  methods  in  physical  geography  are  printed  in  the  Journal  of 
Geography  (R.  E.  Dodge,  Teachers  College,  Columbia  University,  New  York  City),  a  monthly 
magazine  "Devoted  to  the  Interests  of  Teachers  of  Geography."     Price,  $1.00  a  year. 

The  authors  will  welcome  any  suggestions  teachers  may  make,  and,  where  practicable, 
insert  them  in  future  editions. 

Ithaca,  June  10, 1909. 


Vll 


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# 


SUGGESTIONS   TO   TEACHERS 

A  teacher's  manual  for  use  in  connection  with  these  outlines  for  laboratory  and  excur- 
sion work  is  in  preparation  and  will  be  issued  shortly.  In  it  will  be  found  particular 
suggestions  in  regard  to  each  exercise,  together  with  a  list  of  references  for  supplementary 
reading  and  hints  on  the  use  of  lantern  slides,  models,  and  other  material  which  may  be 
available  in  connection  with  these  outlines. 

In  the  following  paragraphs  are  given  a  description  and  suggestions  for  the  use  of  the 
apparatus  needed  in  Exercises  XXII,  XXIII,  and  XXVI.  These  are  inserted  because  this 
method  of  presentation  of  the  subject  is  new,  and  most  teachers  will  be  unfamiliar  with  the 
apparatus  used. 

EXERCISES  XXII   AND  XXIII 

The  Construction  and  Understanding  of  Contour  Maps 

On  a  thorough  understanding  and  appreciation  of  the  significance  of  contour  lines  depends 
the  value  of  all  the  pupil's  later  study  of  topographic  conditions  as  expressed  by  maps  on 
which  they  are  used.  The  simplest  method  of  teaching  the  meaning  of  contour  maps,  where 
there  are  no  laboratory  facilities,  is  for  the  teacher  to  draw  on  the  blackboard  an  outline 
of  a  land  surface  and  on  it  write  in  figures  indicating  elevations  of  different  points  and  having 
the  pupils  copy  this  and  connect  points  of  equal  elevation  with  contour  lines.  This  and 
similar  methods  we  have  found  very  unsatisfactory.  The  apparatus  and  method  advised 
and  outlined  in  this  manual  are  those  used  with  much  success  at  Cornell  University,  where 
they  solved  this  problem  of  teaching  contour  maps  after  various  other  methods  had  been  tried 
with  indifferent  results.  The  apparatus  is  subject  to  several  modifications.  Where  space 
and  funds  are  available,  it  will  be  found  well  worth  while  to  install  a  large  tank  with 
a  crank-lifted  platform  as  described  below.  This  apparatus  can  also  be  used  for  study  of 
erosion  and  depositional  processes.  (See  following  pages  devoted  to  such  exercises.)  If  the 
dimensions  given  are  too  large,  they  can  readily  be  scaled  down  to  meet  the  space  conditions 
of  the  laboratory  where  the  apparatus  is  to  be  installed.  The  working  drawings  will  make 
the  construction  of  the  apparatus  feasible  in  any  localit}^  or  the  Geography  Supply  Bureau, 
Ithaca,  New  York,  will  quote  prices  on  duplications  of  various  sizes. 

Description  of  Large  Tank  and  Screw-crank  Platform 

A  large  square  wooden  tank,  made  water  tight,  eight  feet  on  the  side  and  sixteen  inches 
deep.  This  tank  is  used  to  hold  a  body  of  standing  water  whose  level  may  be  adjusted,  to 
suit  the  requirements  of  the  exercise,  by  means  of  a  series  of  holes  (bored  in  the  side)  fitted 
with  removable  plugs. 

A  solidly  built  square  platform  five  feet  six  inches  on  the  side.  This  is  intended  to  hold 
the  sand,  clay,  or  other  materials  of  which  a  land  form  is  to  be  molded. 

In  the  four  corners  of  this  platform  threaded  iron  collars  are  inserted,  and  into  these  are 
screwed  heavy  iron  cranks  which  serve  at  once  to  support  the  platform  and  raise  and  lower  it. 
The  threads  on  the  cranks  and  in  the  collars  are  coarse,  some  ten  or  twelve  turns  to  the  inch. 
The  ends  of  the  cranks  are  pivoted  in  loosely  fitting  iron  sockets  screwed  fast  to  the  bottom 
of  the  outer  tank. 

ix 


MAKING  READY  FOE   THE   EXERCISE 

When  this  apparatus  is  set  up,  the  whole  platform,  with  its  incumbent  model,  can  be  S~ 

rapidly  raised  and  lowered  at  will,  by  turning  the  cranks  simultaneously. 

The  materials  used  in  building  up  the  model  are  sand  and  clay,  with  enough  plaster 
of  paris  admixed  (a  very  small  quantity  serves  this  purpose)  to  give  the  forms  sufficient 
firmness  to  stand  up  without  slumping  when  immersed  in  water  for  some  time.  Just  before 
the  beginning  of  the  exercise  the  outer  tank  is  filled  with  water,  the  water  level  being  adjusted 
by  means  of  the  plugs  on  the  one  side,  and  the  platform  is  lifted  by  means  of  the  cranks  until 
the  water  surface  coincides  with  the  level  of  the  lowest  parts  of  the  land  surface. 

The  drawing  shows  the  apparatus  adjusted  with  land  form  modeled  ready  for  the  class 
to  begin  work.  The  square  outline  of  the  map  to  be  constructed  will  then  be  expressed 
by  the  square  outline  of  the  platform  top.  Working  drawings  of  the  apparatus  are  given 
in  the  accompanying  drawing. 

Conduction  of  Exercise 

To  conduct  the  contour  mapping  exercise  proceed  as  follows :  After  a  suitable  scale  for 
the  map  has  been  adopted,  outline  of  the  model  sketched,  and  its  salient  points  located,  the 
pupils  have  made  a  map  on  which  the  0  or  sea-level  contour  is  expressed  by  the  outline 
of  the  land  form.  Then  a  contour  interval  is  adopted.  (A  one-inch  interval  will  be  found 
practicable  for  this  size  model.)  Next,  with  a  pupil  to  operate  each  crank,  lower  the  model 
through  the  vertical  distance  of  the  contour  interval.  Be  sure  that  the  outflow  of  the  tank 
is  sufficiently  large  to  allow  the  water  displaced  to  escape  rapidly.  Then  the  class  proceeds 
with  the  sketching  of  the  first  contour.  This  procedure  is  repeated  as  many  times  as  neces- 
sary to  complete  the  map. 

Where  the  installation  of  the  large  screw-tank  apparatus  is  not  feasible  the  following 
modification  may  be  used.     This  serves  fairly  well  with  small  classes. 

Instead  of  the  platform  with  screw  cranks  and  land  form  modeled  of  clay  and  sand  a  much 
smaller  plaster  of  paris  model  is  used.  This  is  a  model  after  an  ideal  land  form  which  the 
United  States  Geological  Survey  uses  in  describing  contour  maps.  (See  one  of  the  United 
States  Geological  Survey  Folios.)  In  connection  with  it  a  small  tank  of  water  is  used,  filled 
to  the  brim.  In  this  tank  are  piled  a  number  of  waterproof  fiber  boards  of  uniform  thickness 
and  heavier  than  water.  The  plaster  model  is  placed  on  this  pile  of  fiber  boards  and  the 
water  level  adjusted  to  the  edge  of  the  modeled  land  area.  Successive  contour  lines  are 
located  by  removing  successive  sheets  of  the  fiber  board.  Otherwise  the  procedure  is 
the  same.  This  equipment  is  also  simple  of  construction,  but  if  preferred,  can  be  obtained 
through  the  Geography  Supply  Bureau  of  Ithaca,  New  York. 

EXERCISE   XXVI 

If  the  tank  and  land  model  are  not  available,  a  sand  table  or  sink  of  sufficient  dimensions 
can  be  arranged  to  carry  out  this  experiment. 

In  building  up  the  land  form  use  molder's  sand  and  powdered  clay  in  alternate  layers. 
Have  the  clay  layers  quite  thin,  one  half  inch  on  the  average.  Build  the  model  so  that  it  has 
variety  in  topography,  but  give  it  the  general  surface  of  a  plain  with  a  somewhat  steep  slope 
toward  the  front.  It  will  be  well  to  incline  the  platform.  If  the  clay  layers  are  not  sufficiently 
hard  to  cause  waterfalls,  a  little  plaster  of  paris  may  be  added.  To  get  good  deltas  the  water 
at  the  edge  of  the  land  form  must  not  be  too  deep,  and  must  remain  at  a  uniform  level. 
The  pupils  should  read  through  the  whole  exercise  before  the  experiment  is  begun  so  that  ( 

they  will  be  on  the  alert  for  the  various  phenomena.     (For  further  details  see  article  by  Tarr 
and  von  Engeln,  in  Journal  of  Geography,  Vol.  VII,  1908,  pp.  73-85.) 


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COMPLETE   LIST   OF   MATERIALS   NECESSARY   FOR  USE   IN 
CONNECTION   WITH   THESE   OUTLINES 

(Some  of  these  may  be  omitted  according  to  the  discretion  of  the  teacher. ) 

For  Each  Student 

(a)  Material  which  the  student  can  bring  to  the  classroom  from  home  at  different  times. 
Apple,  knitting  needle,  string,  pencil,  ruler,  plain  paper,  watch  (where  possible),  small 

bag  or  basket,  steel  knife  or  scratch  point,  window-glass  fragment,  drinking  glass,  piece  of 
candle,  several  small  pieces  of  cheese  cloth,  several  needles,  coal  fragment,  baseball. 

(b)  Material  which  student  may  purchase. 

Box  of  colored  pencils  (six  different),  cost  10  cents.  Map  of  the  United  States  18x28 
inches  with  contours,  published  by  United  States  Geological  Survey.  Should  be  mounted 
on  cloth.     Cost  10  cents. 

(c)  Material  to  be  furnished  by  the  school. 

Small  desk  globe,  simple  compass  dividers,  several  glass  plates  4x4  inches  approximately. 
Copy  of  weather  map,  any  date.  Bar  magnet.  Several  test  tubes.  Mineral  and  rock  fragments, 
unlabeled,  following  varieties :  quartz  crystal,  orthoclase  and  plagioclase  feldspar,  hornblende, 
halite,  biotite  and  muscovite  mica,  calcite,  gypsum,  iron  pyrites,  dolomite,  hematite,  mag- 
netite, granite,  sandstone,  fossiliferous  limestone,  schist,  pumice,  cellular  lava,  obsidian, 
rhyolite,  trachyte,  syenite,  gabbro,  basalt,  conglomerate,  shale,  gneiss,  quartzite,  slate,  marble, 
rock  with  lichen  attached,  rounded  stream  pebbles,  residual  soil  from  granite,  residual  clay 
from  limestone. 

United  States  Geological  Survey  topographic  sheets  (should  be  mounted  on  cloth)  as 
follows :  — 

Montross,  Maryland-Virginia.  Lake  Placid,  New  York. 

Fargo,  North  Dakota-Minnesota.  Saw  Tooth,  Idaho. 

Donaldsonville,  Louisiana.  Chief  Mountain,  Montana. 

Winterville,  North  Carolina.  Spokane,  Washington-Idaho. 

Mt.  Carrizo,  Colorado.  Granite  Range,  Nevada. 

Syracuse,  Kansas.  Bright  Angel,  Arizona. 

Kearney,  Nebraska.  Yosemite  California  Quadrangle. 

Centerpoint,  West  Virginia.  Map  of  Yosemite  Valley,  California. 

Caldwell,  Kansas.  Shasta,  California. 

Whitewater,  Wisconsin.  Shasta  Special,  California. 

Weedsport,  New  York.  Cucamonga,  California. 

Niagara  Falls  and  Vicinity,  1901,  New  York.  San  Francisco,  California. 

Cleveland  and  Vicinity,  Ohio.  Tamalpais,  California. 

St.  Louis,  Missouri.  Boothbay,  Maine. 

Denver,  Colorado.  Barnegat,  New  Jersey. 

Monterey,  Virginia- West  Virginia.  Port  Orford,  Oregon. 

Delaware  Water  Gap,  Pennsylvania-New  Jersey.       Van  Horn,  Texas. 

Mt.  Mitchell,  North  Carolina-Tennessee.  Crater  Lake  Special,  Oregon. 

Farmville,  Virginia.  Map  of  Home  Region,  if  published. 

xiii 


For  General  Class  Use 

(a)  Material  of  which  the  teacher  may  secure  the  rise  without  cost. 

An  egg,  saucer,  bottle,  pebbles,  shears,  field  soil  from  beneath  sod,  fruit  jar,  piece  of 
muslin,  daily  weather  map. 

(b)  Material  to  be  furnished  by  school.     (Note.  —  Much  of  this  material  can  probably  be 
borrowed  from  the  physics  and  chemistry  laboratories  of  the  school.) 

Several  wall  maps  of  different  scale. 

Wall  map  of  the  United  States,  showing  railway  lines. 

Chart  #  14  of  the  Mississippi  River  Commission. 

Land  model  tank  (see  Suggestions  to  Teachers). 

Several  yardsticks. 

Spray  nozzle  and  rubber  hose. 

Several  magnetic  compasses. 

Air  pump. 

Glass  tube  35  inches  long,  closed  at  one  end. 

Bottle  of  mercury. 

Funnel. 

Mercury  barometer. 

Several  thermometers. 

Bottle  of  alcohol  or  ether. 

Simple  rain  gauge. 

Several  sheets  of  wrapping  paper. 

Wooden  rod. 

Sheet  of  white  cardboard. 

Several  hammers  (geological,  if  possible). 

Dilute  hydrochloric  acid. 

Several  glass  stirring  rods  or  dropping  bottles. 

Labeled  hand  specimens  of  the  minerals  and  rocks  listed  on  preceding  page. 

(c)  Supplemental.     Material  which  may  be  used  if  available. 
Meteorological  instruments. 

Hand  specimens  of  iron,  gold,  silver,  copper,  lead,  and  zinc  ores. 
Lantern  slides  for  quizzes. 

Note.  —  If  teachers  find  difficulty  in  securing  any  of  these  materials,  it  is  suggested  that 
they  apply  to  the  Geography  Supply  Bureau,  Ithaca,  New  York. 

Cross-section  paper  needed  will  be  found  at  the  end  of  the  manual. 


c 


XIV 


INDEX 


Exercise  w. 
Exercise  w. 
Exercise  w. 
Exercise  W. 
Exercise  #_ 
Exercise  # 
Exercise  W. 
Exercise  W- 
Exercise  W- 
Exercise  #_ 
Exercise  W~ 
Exercise  #_ 
Exercise  W. 
Exercise  #_ 
Exercise  W. 
Exercise  w.. 
Exercise  W. 
Exercise  W- 
Exercise  #.. 
Exercise  ff . 
Exercise  w. 
Exercise  W. 
Exercise  $.. 
Exercise  W. 
Exercise  W. 


XV 


( 


e 


INDEX 


§ 


Exercise  #_. 
Exercise  #_. 
Exercise  #_. 
Exercise  #.. 
Exercise  #_. 
Exercise  #._ 
Exercise  #.. 
Exercise  #.. 
Exercise  #_ 
Exercise  F_. 
Exercise  #- 
Exercise  #_ 
Exercise  #.. 

* 

«  Exercise  #.. 

Exercise  #.. 

Exercise  #„. 

Exercise  #_. 

Exercise  #_ 

Exercise  #.. 

Exercise  ff. 
I  Exercise  #.. 

Exercise  #._ 

Exercise  #.. 

Exercise  #. 
wi/'  Exercise  #_ 


xvn 


( 


THE   EARTH   AS   A   WHOLE 


Materials. 
Purpose. 

A  sphere 
defined. 


I.— SHAPE  AND  SIZE  OF  THE  EARTH 

For  Each  Student.  —  Desk  globe.     Apple.     Knitting  needle.     String.     Pencil.     Ruler. 

To  gain  an  appreciation  of  the  form  of  the  earth  and  its  dimensions. 

Give  a  definition  of  a  sphere  in  as  few  words  as  possible.     


Name  three  objects  that  are  spheres. 


The  earth 
an  oblate 
spheroid.       sphere  ? 


Is  an  apple  a  perfect  sphere  ?     How  do  most  apples  differ  from  a  true 


What  is  the  name  given  a  spherical  body  that  is  flattened  at  the  poles  ?     

Make  a  sketch  to  show  how  an  oblate  spheroid  differs  from  a 

true  sphere. 


%) 


How  much  is  the  earth  flattened  at  the  poles?     

Why  are  globes  always  made  as  true  spheres,  though  the  earth  is  an  oblate  spheroid  ? 

Meaning  of  What  is  meant  by  the  diameter  of  a  sphere?     

diameter 
and  circum- 
ference. 

1 


Thrust  the  knitting  needle  through  the  center  of  the  apple,  and  with  a  ruler  measure  the 
diameter  of  the  apple.     What  is  meant  by  circumference  ? 


With  the  string  and  ruler  measure  the  circumference  of  the  apple. 
How  many  times  greater  than  the  diameter  is  the  circumference  ? 


.. The  circumference  of  a  sphere  is  always  that  much  greater  than  the 

diameter.     Since  the  diameter  of  the  earth  is  a  little  over  7900  miles,  how  many  miles  is 

the  circumference  ? 


Meaning  of  Thrust  the  knitting  needle  through  the  center  of  the  apple  from  the  stem  end ;  then, 

tanJu         rrestin£  one  end  of  the  needle  on  the  desk,  turn  the  needle  so  that  the  apple  turns  with  it. 
equa  or.         The  needie  ig  tne  axig  on  wj1jcj1  t^e  appje  rotates.     What  terms  would  you  apply  to  the  two 

ends  of  the  axis  ?    What  does  this  experiment 

illustrate  with  regard  to  the  earth  ? 


What  is  the  circumference  of  the  earth  midway  between  the  poles  called  ? 


_ Mark  the  equator  on  the  apple.     Make  a  drawing  of  a  sphere, 

shading  it  so  that  it  appears  round.     On  it  mark  the  equator  and  the  poles. 


CI 


J 


II.  — PROOFS  THAT  THE  EARTH  IS  A  SPHERE 

Materials.  For  Each  Student.  —  Desk  globe.     Pencil. 

For  General  Class  Use.  —  An  egg.     Saucer.     Bottle.     Pebbles.     Book. 
Purpose.  To  show,  by  simple  proofs,  that  the  earth  has  a  spherical  form. 

By  journeys  What  did  people  believe  the  shape  of  the  earth  to  be  when  Columbus  started  on  his  first 

around  the 

earth.  voyage  ? 


What  did  he  believe?     

What  expedition  was  the  first  to  make  the  voyage  completely  around  the  earth  and  return  to 

its  starting  place?     

Push  your  finger  around  the  globe  from  east  to  west ;  from  north  to  south  ;  in  other  directions. 
In  each  case,  if  you  follow  a  straight  course,  do  you  come  back  to  the  point  where  you  started  ? 

Would  that  be  possible  if  the  earth  were  flat  ?     This 

proves  that  the  earth  is  a  curved  body.    But  does  it  prove  it  to  be  a  sphere  ?    

Could  you  do  the  same  thing  on  a  body  shaped  like  an  egg?     It  is  a  longer 

distance  around  an  egg  in  some  directions  than  in  others.    Is  this  true  of  a  sphere  ?   

Is  it  true  of  the  globe  ?     

By  means  Examine  your  desk  globe  to  see  that  every  part  of  its  surface  is  curved.     Place  it  in  the 

of  eclipses     sunlight  so  that  its  shadow  will  fall  on  the  floor.     What  is  the  outline  of  the  shadow  ? 
of  the 

moon-  Turn  the  globe  in  various  positions.    Does  the 

shadow  change  in  form  ?      Try  the  same  experiment  with  several  objects, 

such  as  a  bottle,  a  pebble,  a  saucer,  an  egg.     What  is  the  result?     


Does  any  other  object  than  a  sphere  always  cast  a  circular  shadow? 

3 


Sometimes  the  earth's  shadow  is  cast  on  the  moon,  when  the  earth  comes  between  the  sun  and 

moon.    This  is  called  an  eclipse.    Have  you  ever  seen  an  eclipse  of  the  moon  ?     

Describe  it.     


The  shadow  of  the  earth  is  always   round   in  such  an  eclipse.      What  does  that  prove? 

By  gradual            Place  an  object  on  the  flat  surface  of  your  desk.    When  your  eye  is  above  the  level  of  the 
disappear- 
ance of  desk  top,  can  you  see  this  object  from  all  points  of  view  ?    Is  the  same  true 

objects  in 

tance  °^  an  0DJec^  placed  on  the  curved  surface  of  a  globe?     Stick  a  pin  in  the 

globe  and  turn  the  globe.     As  it  turns  away  from  you  the  pin  slowly  disappears  from  view. 

Which  end  of  the  pin  disappears  first?     

Where  are  the  most  level  places  on  the  earth  ?     

What  part  of  a  ship  at  sea  is  first  seen 

as  it  comes  toward  you?     Make  a  drawing  to 

show  this.     (See  Fig.  6,  Text-book.)     Then  make  a  drawing  to  show  what  would  be  the  case 
if  the  earth  were  flat. 


Objects  disappear  on  the  curved  earth  at  a  regular  rate,  no  matter  in  which  direction  one 
looks.     This  rate  is  8  inches  the  first  mile,  32  inches  the  second  mile,  and  so  on.     The  rate  is 


# 


the  square  of  the  number  of  miles  times  8  inches.     How  much  will  the  disappearance  be  at 

the  third  mile  ?     (3  x  3  =  9  x  8  =  72  inches.)     How  much  at  the  fourth  ?    

, The  fifth? 


Would  it  be  true  that  an  object  would  disappear  at  a  regular  rate  in  all  directions  and  in  all 

places  on  a  cylinder ?     On  an  egg?    On  any  other  than  a 

spherical  body  ?    What  then  do  you  conclude  in  regard  to  the  form  of  the 

earth?     

By  position           Heavenly  bodies  also  change  position  at  a  regular  rate  when  viewed  from  different  points 
of  the           on  fjhg  earth.     At  the  equator  the  north  star  is  on  the  northern  horizon,  no  matter  at  what 
part  of  the  equator  one  stands.    At  the  north  pole  it  is  overhead.    Where  would  it  be  half- 
way between  pole  and  equator?     Could  this 

be  true  if  the  earth  were  egg  shaped? Or  pear  shaped?     

f 

Or  cylinder  shaped  ?     


Other 
spheres 
in  the 
heavens. 


Name  other  spherical  bodies  in  the  heavens. 


What  would  be  the  appearance  of  the  earth  if  it  could  be 


seen  from  the  moon  ?     

Make  a  drawing  to  scale  (below)  to  show  the  comparative  size  of  the  earth  and  moon.    (Text-book,  p.  1.)    Of 
the  earth  and  sun.    (Text-book,  p.  3.) 


What  is  an  eclipse  of  the  sun  ? 


How  does  this  prove  that  the  moon  is  a  sphere  ? 


o 


cc 


III.  — WORLD   MAPS 

Materials.  For  Each  Student.  —  Pencil  (sharp).    Ruler.    Small  desk  globe.    Several  sheets  of  blank  paper. 

For  General  Class  Use.  —  Maps  of  different  scale.     Pair  of  shears.     Several  baseballs.     Sheet 
of  wrapping  paper. 

Purpose.  To  teach  the  meaning  of  scale,  and  to  show  the  difficulty  of  representing  the  curved  earth's 

surface  on  a  flat  map. 

What  is  the  greatest  distance  that  you  can  see  in  any  one  direction  in  your  locality  ? 

(Express  in  city  blocks  or  miles.)     , 

If  you  wished  to  represent  five  miles,  or 

five  city  blocks,  on  a  piece  of  paper  the  width  of  this  note  book,  what  would  you  need  to  do  ? 


Meaning 
of  scale. 


1 


As  applied  to  maps,  what  is  the  term  used  to  express  this  scheme  ? 


Draw  below  a  distance  of  6  miles  expressed  by  a  scale  of  f  inch  =  1  mile. 


How  must  the  scale  of  a  map  vary  with  the  size  of  the  area  represented  ? 


If  a  map  of  an  area  5  miles  square,  and  one  of  an  area  1000  miles  square  were  both  of  the 
same  size,  which  would  show  more  detail  ?     

Could  a  road  25  feet  wide  be 

accurately  located  by  double  lines  on  a  map  drawn  to  the  scale  1  inch  =  1  mile  ?     (Make  the 
calculation  on  a  separate  sheet  of  paper  and  copy  the  calculations  and  your  conclusion  below.) 


Examine  different  maps,  as  directed  by  the  teacher,  and  note  in  the  space  below  the  areas 
they  represent  and  what  scales  are  used. 


Name  of  Map 

Scale  Used 

Area  represented  in  Square  Mii.es  (to  be  deter- 
mined by  Use  op  the  Scale) 

Explain  the  significance  of  the  fraction  (such  as  ^^)  used  on  maps  in  connection  with 
the  scale.    


Globes.  What  form  would  give  the  most  accurate  representation,  in  miniature,  of  the  whole  world  ? 

What  are  some  of  the  disadvantages  of  a 

globe  map;  for  instance,  for  use  in  books? * 


Plane 

surface 

maps. 


Try  to  fit  a  sheet  of  paper  over  one  half  or  more  of  your  desk  globe.     What  is  the  result? 

Examine  a  baseball.     How  many  parts  are 

there  to  its  cover?     What  proportion  of  the  ball's  surface  does  each  part  of 

the  cover  fit  over?     Draw  an  outline  of  one  of  these  parts. 


Why  was  such  a  shape  adopted  for  baseball  covers  ? 


Cut  a  piece  of  paper  of  the  same  shape, 

and  large  enough  to  use  in  covering  one  half  of  your  desk  globe.     Apply  it  to  your  globe  in 
different  positions.     What  parts  of  what  continents  can  you  cover  in  different  positions? 


What  great  objection  to  making  world  maps  of  this  shape  does  this  experiment  disclose? 


Examine  Figs.  28,  444,  and  515  in  Text-book  to  see  the  shape  of  some  of  the  maps  used  to 
represent  the  earth  on  a  flat  surface.     What  is  the  result  of  your  observations?     


o 


G 


# 


Materials. 


IV. —MAP   CONSTRUCTION 

For  Each  Student.  —  Pencil.     Ruler.     Desk  globe.     Dividers. 
For  General  Class  Use.  —  Several  wall  maps. 


Purpose.  To  gain  an  understanding  of  the  essential  features  of  a  map,  methods  of  map  projection,  and 

their  application. 

Meaning  of  In  ancient  times  the  land  of  the  world  was  thought  to  be  longer  in  an  east  and  west  direc- 

latitude         tion  than  in  the  north  and  south  direction.     Figure  1  is  a  copy  of  an  early  map  of  the  world, 
and 

longitude.     as  Revised  by  Ptolemy.     In  what  years  did  he  live  ?    


Fig.  1.  — Ptolemy's  Map  of  the  World. 
Latin  was  then  the  language  of  the  Mediterranean  region.     What  is  the  meaning  of  the  Latin 

word  longus  ?     Of  the  Latin  word  lotus  ?    

Which  lines  on  Ptolemy's  map  are  used  to  mark  off  the  long  directions  ?    

Which  lines  to 

mark  off  the  width?     

11 


Why  were  the  lines  running  north  and  south  called  lines  of  longitude  ? 


called  lines  of  latitude  ? 


..    Why  were  those  running  east  and  west 
Where   did   Ptolemy  start   num- 


bering the  lines  of  latitude? 


Latitude 
and 

longitude 
on  the 
globe. 


The  lines  of  longitude?     

What  latitude  would  one  have  north  of  a  zero  point? 
What  latitude  south  of  a  zero  point? 


What  is  the  zero  line  of  latitude  on  your  globe?     

Do  you  know  of  any  similar  natural  line  which  could  be  used  for  a  zero  line  of  longitude  ? 

Through  what  city  does  the  zero  line  of  longitude  on  your  globe 

pass? Might  not  Paris  or  Washington  be  used? 

• Why,  then,  does  the  zero  line  for  reckoning  longitude  often  vary  with  the 

country  where  the  map  is  made  ?     

Consult  several  maps  and  state  which  line  is  most  commonly  used.     


Where  is  Greenwich?     

Trace  several  lines  of  latitude  around  the  globe  ?     Why  are  these  circles  called  "  parallels 

of  latitude"?     

Trace  in  the  same  manner  several  lines  of  longitude.     Are  they  parallel?     


At  what  two  points  do  they  meet?     

The  longitude  lines  are  called  meridians  of  longitude. 

If  you  have  studied  geometry,  prove  that  two  straight  lines  can  intersect  at  only  one 
point. 


12 


After  examining  your  globe  again,  will  you  agree  that  with  the  exception  of  the  poles  this 
proof  also  applies  to  the  intersection  of  the  parallels  of  latitude  and  the  meridians  of  longi- 
tude?          Bearing  this  in  mind,  can  any  one  point 

on  the  earth's  surface  (except  the  north  and  south  poles)  have  more  than  one  latitude  and  one 

longitude?     On  your  desk  globe  locate  the  city  which  has  (nearly)  60° 

North  Latitude  and  30°  East  Longitude  from  Greenwich.     

What  is  the  longitude  of  this  city,  starting  from  Washington  as  the  prime  meridian  0°? 

Determine  from  your  desk  globe  the  latitude 

and  longitude  (Greenwich  meridian)  of  your  home  region.      

My  home,     ,     is  at    

latitude  and  at     longitude     of  Green- 
wich.    How  can  the  exact  location,  north  or  south  of  the  equator,  of  any  point  on  the  earth's 

surface  be  stated?     

Its  distance  east  or  west  of  any  given  meridian?     


How  many  degrees  are  there  in  the  circumference  of  a  circle?     

In  a  half  circumference?     : A  quarter  circumference?     , 

How  many  degrees  of  north  latitude  can  there  be?     

East  or  west  longitude?     

Assuming  that  the  earth's  circumference  is- 25,000  miles,  what  is  the  length,  in  miles,  of  a 

degree  of  longitude  at  the  equator?     At  the 

poles?     At  60°  N.  or  S.  latitude?  (Use  dividers 

for  measuring  on  the  globe.)    How  do  the  distances 

between  meridians  vary  on  your  globe?     


Plane  Map  makers  have  devised  many  schemes  to  overcome  the  difficulties  of  mapping  a  curved 

surface  surface  on  a  plane  surface.     These  schemes  are  called  projections.     Some  of  these  are  the 

mapping.      Orthographic,  Stereograph ic,  Globular,  Gnomonic,  Homolographic,  Conic,  Polyconic,  Van  der 

Grinten,  and  Mercator's  Cylindrical  projections.     (See  Fig.  2.)     How  do  some  of  these  differ 


in  the  manner  of  representing  meridians  and  parallels  of  latitude? 


13 


100  120  140  ISO  180  180  140  120  100  80   60   40   20   0   20   40   60 

Mercator  Projection 


Van  der  Grlnten  Projection 

« a 


Equatorial  Stereographic  Projection 


Western  Hemisphere 
In  Equatorial  Globular  Projection 


Fib.  2.  —  Various  Projections. 
14 


Why  are  maps  and  charts  of  greater  importance  to  sailors  than  to  any  other  class  of 
people?  


Kemembering  that  sailors  have  instruments  for  determining  latitude  and  longitude,  consider 
and  state  your  reasons  in  answering  the  following :  Which  is  of  more  importance  to  sailors 
—  to  have  distances  between  points  shown  truly  on  a  map,  or  to  have  directions  between 


• 


points  shown  as  straight  lines? 


(The  Mercator  projection  was  invented  by  a  German  whose  name  was  Kramer.  In  Ger- 
man this  word  means  "  retail  merchant."  The  Latin  for  merchant  is  mercator,  and  thus  the 
projection  got  its  name.) 

The  Mercator  projection  was  designed  to  show  all  parallels  and  meridians  as  straight 
lines  at  proportional  distances ;  hence,  directions  as  straight  lines.  Thus  the  sailor  has  sim- 
ply to  draw  upon  the  map  a  straight  line  from  the  point  where  he  is  to  the  point  to  which  he 
wishes  to  sail,  in  a  straight  course.  He  can  then  steer  his  ship  according  to  the  bearings  thus 
obtained. 


15 


a 


o 


Materials. 
Purpose. 


Construct- 
ing a 
map  on 
Mercator's 
Projection. 


V.— THE   MERCATOR   MAP 

For  Each  Student.  —  Dividers.     Sharp  pencil.     Ruler.     Desk  globe. 

The  construction  of  a  Mercator  map;  and  to  get  an  appreciation  of  the  distortion  involved  in 
such  a  map. 

Figure  3  is  a  beginning  of  a  Mercator  Cylindrical  Projection.  The  circle  represents  a 
north  and  south  section  of  the  globe.  The  diameter  of  the  circle  shows  180°  of  the  equator  as 
a  straight  line,  and  this  line  is  continued  into  the  map  diagram  that  adjoins  the  circle.  From 
the  center  of  the  circle  angles  are  laid  off  for  every  15°  north  of  the  equator.  The  line  A-L, 
representing  the  western  edge  of  the  map,  is  perpendicular  to  the  equator  line.  The  length  of 
the  line  parallel  to  A-L  (that  is,  Bx),  and  extending  from  the  end  (B)  of  the  first  radius  north 
of  the  equator,  gives  the  distance  that  the  15°  parallel  of  latitude  of  the  map  is  to  be  drawn 
north  of  the  equator  line.  (The  15°  parallel,  as  drawn,  is  marked  C-D  on  the  diagram.)  In 
the  same  way  the  length  of  the  line  parallel  again  to  A-L,  and  extending  from  the  end  of  the 
radius  of  30°  to  the  15°  radius,  gives  the  distance  that  the  parallel  of  30°  north  latitude  is  to 
be  drawn  above  that  of  15°  north  latitude.  (This,  the  30°  line,  is  marked  E-F.)  Follow  this 
procedure  and  complete  the  drawing  of  the  parallels  for  both  north  and  south  latitude  up  to  75°. 

Draw  the  meridians  of  longitude  at  equal  distances  from  each  other,  and  the  same  dis- 
tance apart  as  the  first  parallel  of  latitude  is  from  the  equator.  Draw  the  0°,  or  prime 
meridian,  through  the  circle  printed  on  the  map. 

On  your  globe,  with  dividers  and  a  ruler,  measure  the  distance  (in  inches)  between  15°  of 

longitude  on  the  line  of  the  equator.    Do  the 

same  along  the  line  of  the  60°  parallel  of  north  [or  south]  latitude.     , 

What  is  the  ratio  between  these  two  distances?     r. 


On  your  map,  as 


drawn,  measure  the  distance  between  the  equator  and  15°  north  latitude.     

Again,  on  your  map,  measure  the  distance  between  52°  30'  north  latitude  and  67°  30'  north 

latitude  (=15°).    What  is  the  ratio  between  these  latter  two  distances? 


From  these  observations  complete  the  following  sentence  :  On  the  Mercator  projection  map, 
the  distortion  in  latitude  distances  is  in  the  same  ratio  as  the 


§ 


and  directions  are  consequently  represented  as  straight  lines. 


17 


a 


a 


c 


f 


Plotting  in  The  little  circle  printed  on  the  map  represents  the  location  of  Washington,  D.C.,  and  is 

I  the  outline    on  the  prime  meridian  as  you  have  drawn  your  map.     From  your  globe  plot  in  the  outlines  of 
pi  North        ^e  continents  of  North  and  South  America. 
America 
and  South 
America. 


Distortion  Compare  the  outline  of  these  continents  on  your  globe  and  on  the  Mercator  map  you  have 

of  the 

Mercator       constructed.     Where  and  how  does  the  Mercator  projection  distort  areas?     

Projection. 


Why,  then,  is  no  scale  of  miles  given  (except  at  times  along  the  equator)  on  a  Mercator  map  ? 


1 Examine  the  maps  in  Figure  2  of  this  Manual 

and,  by  comparison  with  the  globe,  make  observations  as  to  their  correctness  in  representing 

direction  and  distance.     


21 


Curvature 
of  earth 
on  small 
areas. 


Calculate  and  draw  a  line  showing  the  curvature  of  the  earth's  surface  over  a  distance  of 
5  miles,  mapped  on  a  scale  of  1  inch  =  1  mile. 

Note.  —  To  find  the  amount  of  curvature  of  the  earth's  surface  for  any  given  distance,  use  the  following 
rule :  Square  the  number  of  miles  representing  the  distance.  Two  thirds  of  the  resulting  number  represents  in 
feet  the  departure  from  a  straight  line. 

Calculation :  — 

Draw  line  here. 


How  does  this  result  apply  to  the  amount  of  appreciable  areal  distortion  shown  in  maps  of 
small  areas  ?     , 

How  does  it  compare  to  the  amount  of  distortion  on  the  world  maps  ?     


22 


•  UPRIGHT  POST 


\ 

i    \ 


12  M. 
SEPT.  26  * 


\ 


\ 


\ 


\ 


\10  O'CLOCK" 
*SEPT.  26 


Fig.  4.  —  Diagram  of  Apparatus  for  establishing  the  Meridian  by  the  Sun's  Position. 


23 


t 


Material. 


Purpose. 


Determina- 
tion of 
direction 
by  sun's 
position 
and  use  of 
watch. 


Method. 


VI.  —  DETERMINATION    OF    DIRECTION    AND    ESTABLISHMENT    OF    MERIDIAN 

For  Each  Student. — Watch  (when  possible).     Ruler.     Pencil. 

For  General  Class  Use.  —  Rod.     Cardboard. 

To  study  simple  methods  for  determining  the  cardinal  directions  and  for  establishing  a 
meridian  by  the  sun's  position. 

Since  the  sun  apparently  revolves  around  the  earth  from  east  to  west,  it  must  at  some 
time  in  its  daily  course  he  halfway  between  these  two  directions,  and  therefore  where  you 

live  be  due (Add  proper  word.)     At  what  time  between  sunrise  and 

sunset  would  the  sun  be  in  this  position  ?     


With  a  watch  in  hand  we  can  make  use  of  the  sun's  position  to  determine  approximately 
the  cardinal  directions,  i.e.  south,  north,  east,  and  west. 

Stand  facing  the  sun ;  hold  your  watch  so  that  the  hour  hand  points  directly  to  the  sun ; 
then  a  line  from  the  center  of  the  dial,  and  equally  dividing  the  distance  between  the  hour 
hand  and  the  twelve  o'clock  figure,  will  point  approximately  south. 

(To  the  Teacher.  —  Advise  the  students  of  the  amount  that  standard  time  is  slower  or  faster  than  sun  time 
for  your  locality,  and  how  to  apply  the  correction.) 

Try  this  experiment  at  different  hours  of  the  day.     Do  the  results  coincide  ?     


When  is 


Establish- 
ing a 
meridian 
by  sun's 
position. 


there  the  greatest  deviation?     

Is  there  a  deviation  from  day  to  day  ?     

Facing  south,  what  direction  is  at  your  back  ?  To  your  right  ? 

To  your  left?   


Erect  a  thin  rod  of  wood,  or  metal,  six  inches  or  more  high,  exactly  perpendicular  to  the 
middle  point  of  the  long  edge  of  a  stiff  piece  of  white  cardboard.  Put  this  cardboard  on  a 
smooth  table  top,  carefully  leveled,  and  place  the  table  before  a  south-facing  window  with  the 
edge  of  the  cardboard  which  carries  the  rod  toward  the  outside.  Note  the  length  and  direction 
of  the  shadow  which  the  rod  casts  on  the  cardboard  by  marking  on  the  board,  as  accurately  as 
possible,  the  length  and  direction  when  the  shadow  is  shortest.  Do  this  for  several  days.  Set 
down  the  data  on  Figure  4.     Get  these  data,  if  possible,  on  or  near  Sept.  23  or  March  21. 

What  directions  are  determined  by  the  line  of  the  sun's  shortest  shadow  ?    


25 


Suggested  On  a  clear  night  locate  the  north  star  by  means  of  the  "  Big  Dipper,"  as  shown  in  the  diagram  (Fig.  5). 

home  work  How  well  does  your  determination  of  north  by  the  sun's  position  agree  with  the  north  as  determined  by  the 

■fnr 

students         position  of  the  north  star  ?     


NORTH  STAR  . 


** 


/ 


* -*«• 

Fig.  5.  —  Diagram  to  illustrate  Method  of  locating  North  Star  by  Means  of  the  "Big  Djpper." 


26 


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27 


VII.  —  DETERMINATION   OF   LATITUDE   AND   LONGITUDE 

Material.  For  Each  Student.  —  Desk  globe.     Pencil.     Ruler. 

For  General  Class  Use.  —  Rod  and  cardboard  apparatus  used  in  preceding  exercise. 
Purpose.  A  study  of  methods  by  which  latitude  and  longitude  may  be  determined  for  any  given  place. 

Determina-  On  Sept.  23  and  March  21  the  sun  is  vertical  at  the  equator.     If  you  were  at  the  equator, 

tion  of  the  sun  would  then  be  directly  over  your  head  at  noon.     Where  would  it  appear  if  you  were 

latitude 

JLic.e„„A„     at  either  pole?     

suns  noon  r 

altitude.        What  is  the  angular  distance,  in  degrees,  from  a  point  in  the  sky  directly  overhead  to  a  point 

on  the  horizon?    What  is  the  angular  difference, 

then,  between  the  position  of  the  sun  on  those  two  days  to  observers,  one  at  the  equator  and 

the  other  at  one  of  the  poles  ?     How  are  the 

degrees  of  latitude  numbered  as  one  goes  from  the  equator  toward  the  pole?    

. How  do  the  number 

of  degrees  of  the  sun's  height  above  the  horizon  vary  as  one  goes  from  the  equator  to  the  pole  ? 


Complete  this  sentence:   The  numbering  of  degrees  of  latitude  grows   

as  one  goes  from  the  equator  toward  the  pole ;  and  the  altitude  of  the  sun  above  the  horizon 

grows   as  one  goes  from  the  equator  toward  the  pole.     Therefore,  if 

one  observes  at  any  place  the  altitude  of  the  sun  in  degrees,  and  subtracts  that  number  from 

90°,  the  result  will  be  the  number  equal  to  the  degree  of of  the  place. 

The  sun's  apparent  course  is  north  of  the  equator  after  March  21,  increasing  in  altitude 
by  a  certain  amount  every  day  (see  table  on  preceding  page)  up  to  June  21.  To  get  the  latitude 
on  any  day  between  these  two  dates  one  must  add  a  correction  (from  the  table)  to  the  latitude 

as  determined  by  the  above  method.     Why  do  we  add  the  correction  ?     


What  correction  must  be  applied  between  Sept.  23  and  Dec.  21,  when  the  sun  is  decreasing  in 

altitude?     

A  Figure  6  is  a  diagram  of  the  apparatus  used  in  this  exercise. 

29 


B' 


/C 


/a 


C  B 

Fig.  6.  —  Diagram  to  illustrate  a  Method  of  finding  Latitude. 
A-B,  the  length  of  the  rod  ;  C'-B,  the  length  of  the  noon  shadow ;  BCA,  angle  of  the  sun's  altitude. 

Reading  To  read  the  angle  of  the  sun's  altitude,  as  observed,  we  need  first  to  draw  to  scale  our  read- 

the  angle      ing  (as  secured  in  the  preceding  exercise)  of  the  length  of  the  shadow  and  the  length  of  the 
of  the  sun's   r0(j 

If  you  have  studied  geometry,  prove  that  the  angle  B'AC  is  the  angle  of  the  latitude. 
To  obtain  the  exact  latitude,  a  correction  must  be  applied  to  this  angle,  as  you  have  learned 
above. 


30 


or  Th_    ■* 


Suggested 
home  work 
for 
students. 


Next  we  need  to  use  the  protractor  printed  on  the  cardboard  accompanying  this  exercise 
(Fig.  7).  This  is  simply  a  half  circle  whose  circumference  is  marked  off  in  degrees  and  half 
degrees.  Use  the  shears  to  cut  it  out  carefully,  as  directed  on  the  figure.  Place  the  marked 
center  of  the  protractor  accurately  on  the  extremity  of  the  line  of  the  shadow  (by  means  of  a 
pin  stuck  through  the  cardboard).  Let  the  base  line  of  the  protractor  coincide  with  the  line 
representing  the  shadow.  Then  read  off  the  angle  made  by  a  line  from  the  center  of  the  pro- 
tractor to  the  top  of  the  line  representing  the  height  of  the  rod ;  that  is,  the  angle  BCA. 

The  angle  is degrees. 

The  correction  is degrees. 

The  latitude  as  determined  is degrees  north  latitude. 

How  does  this  compare  with  the  latitude  as  mapped  on  your  globe,  or  any  other  map  of 

your  locality?     

The  angle  of  the  altitude  of  the  north  star  is  equal  to  the  latitude  of  the  place  where  the  observation  of 
the  north  star's  position  is  made.  The  same  reasoning  that  was  applied  to  the  position  of  the  sun  at  the 
equator  and  the  poles  applies  also  to  the  north  star,  except  that  the  positions  are  reversed  ;  i.e.  the  north  star 
is  in  the  zenith  (directly  overhead)  at  the  poles  and  on  the  horizon  at  the  equator.  Therefore  the  altitude  of 
the  north  star  gives  the  degree  of  latitude  directly.  Moreover,  the  north  star  does  not  change  in  position  from 
day  to  day  as  does  the  sun ;  therefore,  the  observation  can  be  made  on  any  clear  night  and  no  corrections 
need  be  applied.     (It  is  not  deemed  worth  while  to  bring  in  here  the  variation  between  culmination  points.) 

Fasten  the  protractor,  by  tacks,  to  a  smooth  board,  as  illustrated  in  Figure  8.  From  the  center  point 
suspend  a  split  shot  by  a  thread  for  a  plumb  bob,  as  shown  in  Figure  8. 


r  -zs—-  ■"■- -rrr 


CENTER 

■*!► >■ 

9 

9 

_,&                   TACK 

TACK 

V 

*#/ 

vy 

V? 

>0 

TJ 

s 


BOARD 


V 


Fig.  8.  —  The  Protractor  used  as  a  Quadrant  Instrument. 

Determina-  We  are  now  ready  to  make  the  reading.     Go  to  some  point  where  the  horizon  line  is  uninterrupted, 

tion  of  the  Point  one  end  of  the  board  (as  indicated  by  the  arrow)  toward  the  north  star,  allowing  the  plumb  bob  to 

latitude  by  swing  freely.     When  you  have  pointed  the  board  accurately  at  the  north  star,  hold  the  thread  of  the  plumb 

observation  bob  firmly  at  the  position  to  which  it  has  swung.     Now  read  the  angle  between  the  present  position  of  the 

tf  the  plumb  bob  and  that  which  it  had  when  the  board  was  held  horizontally.     Make  the  observation  a  number  of 

WiOitb.  star,  times  and  set  down  the  result  as  indicated  on  page  53. 


31 


Reading  No.  1.  —  Angle 

Reading  No.  2.  —  Angle 

Reading  No.  3.  —  Angle 

Reading  No.  4.  —  Angle ' 

Average 

How  does  this  result  compare  in  accuracy  with  that  obtained  by  your  sun  observation  ? 


It  is  by  application  of  these  methods,  with  accurate  instruments  and  refined  corrections,  that  sailors  and 
explorers  determine  their  latitude.     Find  out  what  a  sextant  is. 

Determina-  (Use  your  desk  globe  in  finding  answers  to  these  questions.)     How  many  degrees  are 

tion  of 

longitude,      there  in  the  circumference  of  a  circle  ?     How  many  hours  does  it 

take  the  sun  to  seemingly  go  around  the  earth  ?     

Therefore,  over  how  many  degrees  of  longitude  does  it  pass  in  one  hour  ?     


Is  there  any  difference  in  the  number  of  degrees  of  longitude  the 

sun  passes  over  at  the  equator  and  at  other  latitudes,  such,  for  example,  as  45°  N".  latitude  ? 

When  it  is  noon  at  Washington  on  a  certain  day,  what  time  is  it  on  the  same 

meridian  to  the  north  and  south  of  Washington  ?     

Where  does  the  sun  rise?     Where  does  it  set?     

Which  places  have  noon  first  on  a  certain  day,  those  to  the  east  or  to  the  west?     ' 

If  at  the  same  actual  time  it  is  noon  at  Greenwich,  Eng- 
land (consult  your  globe),  and  seven  o'clock  in  the  morning  at  Philadelphia,  U.S.,  what  is  the 

longitude  of  Philadelphia  as  compared  to  that  of  Greenwich?     


If  now  you  set  a  very  accurate  watch  (chronometer)  exactly  at  noon 

for  Greenwich,  or  any  meridian,  and  then  start  from  there  on  an  exploring  expedition  to 
South  America,  how,  by  consulting  this  chronometer,  can  you  tell  the  longitude  of  different 

points  in  South  America?      


What  advantage  would  there  be  in  carrying  several  chronometers,  all  accurately  set  for  Wash- 
ington time,  or  that  of  some  other  meridian?    


32 


If  there  is  a  telegraph  line  extending  from  a  place, 

of  which  you  know  the  position,  to  one  whose  longitude  you  wish  to  determine,  how  could  the 

telegraph  be  utilized  to  great  advantage  in  the  determination  ?     A 


33 


Materials. 


Purpose. 


Day  and 
night. 


VIII.— ROTATION  AND  ITS  EFFECTS 

For  Each  Student.  —  Desk  Globe.     Dividers. 

For  General  Class  Use.  —  Cardboard  and  Rod  Apparatus. 

To  understand  how  rotation  governs  daily  change  in  time  ;  the  significance  of  standard  time; 
and  of  date  line. 

Place  your  globe  in  a  strong  light.     How  much  of  it  is  illuminated?     

How  much  of  it  is  in  the  shadow?     What  do  these  areas  determine 

on  the  earth,  when  illuminated  by  the  sun?     

Between  the  lighted  and  unlighted  parts  is  a 

belt  all  around  the  globe  which  is  partly  lighted  and  partly  in  shadow.     To  what  times  in 

the  day  would  this  belt  correspond?     


Sunrise  Which  way  does  the  sun  seem  to  move? 

and  sunset. 


rotating,  in  which  direction  must  it  turn? 


If  the  sun  is  standing  still  and  the  earth  is 


Slowly  rotate  the  globe  in  the  same  direction. 


Is  it  moving  clockwise  or  counter-clockwise?     

Stop  the  rotation  when  the  conditions  are  such  that  the  sun  is  just  rising  over  your  home. 

Where  is  it  then  setting?     

Where  is  the  twilight  zone?     


Difference  How  long  does  it  take  the  earth  to  make  one  complete  rotation  ? 

in  time. 


Look  on  the  globe  to  see  how  many  degrees  of  longitude,  east  and 

west,  are  marked  on  the  equator.     What  is  the  sum  of  these? 

How  many  degrees,  then,  must  the  sunrise  pass  over  in  one  hour? 

In  two  hours?     In  six  hours?     Rotate 

35 


the  globe  to  see  that  the  sunrise  extends  farther  and  farther  westward  on  the  equator  as  the 

globe  rotates.     Is  the  same  thing  true  at  latitude  45°?     At  latitude  60°? 

Does  an  object  move  faster  or  slower  at  the  equator  than  at  latitude  45°? 

Why  does  the  sunrise  pass  over  the  same  number  of  degrees  of  longi- 
tude in  an  hour  in  the  two  places?     

Now,  state  why  there  is  an  hour's  difference  in  sunrise 

at  every  fifteenth  degree.       

Is  there  the  same  difference  in  noon?     In  sunset? 

To  the  north  of  the  equator?     To  the  south  of  the  equator  ? 

How  much  difference  in  time  is  there  in  one  degree?     

Is  the  time  of  day  earlier  or  later  to  the  east?     .. 

To  the  west?     What  about  the  time  north  and  south  along  a  given 

meridian?      . 

Problems.              When  it  is  sunrise  at  70°  west  longitude,  is  it  before  or  after  sunrise  at  100°  west  longi- 
tude?          How    much   is   the   difference? 

What  is  the  difference  in  time  of  sunrise  be- 
tween 70°  west  longitude  and  10°  west  longitude  ?     

Between  70°  west  longitude  and  10°  east  longitude?     

When.it  is  midday  at  your  home,  where  is  it  midnight?     

When  the  people  in  London  (at  0°  Long.)  are  rising,  say  at  7  o'clock,  what 

is  the  time  at  your  home?     By  study  of  your 

globe  find  the  difference  in  time  between  (a)  Chicago  and  San  Francisco;     

(b)  New  York  and  Peking ;     (c)  New  York  and  Chicago ;     

(d)  New  York  and  Rome.      In  each  case  state  which  city  has  the  earlier  time. 


Local  time.  (Note.  —  Use  the  cardboard  and  rod  apparatus,  see  Exercise  VI.) 

36 


On  a  board  placed  in  the  sunlight  set  up  a  rod  about  six  inches  high.  At  half-past 
eleven  mark  with  a  pencil  where  the  end  of  the  shadow  of  the  rod  falls  on  the  board ;  also 
marking  the  time  on  the  board.  Be  sure  that  your  watch  is  exactly  right.  Every  five  min- 
utes after  that,  mark  the  position  (and  time)  of  the  end  of  the  shadow  until  half-past  twelve. 
Then  connect  the  points.  Carefully  measure  (with  dividers)  the  distance  between  the  points 
marked  and  the  base  of  the  rod.     Which  point  is  the  shortest  distance  from  the  rod  ?     That 

point  marks  the  time  of  local  noon.     Why  is  that  so?     


Was  it  also  noon  by  your  watch? 

If  not,  how  much  difference  was  there  ?     


Standard  What  objection  is  there  to  the  use  of  local  time? 

time. 


How  have  the  difficulties  been  met? 


Why   should   Greenwich   be   chosen   as   the   place   to   start   in   reckoning    standard   time? 


On  what  meridian  is  the  standard  time  one  hour  later  than  at  Greenwich? 
Two  hours?      


Five  hours?     On  the  outline  map  of  the  United 

States  (Fig.  9)  locate  the  meridians  75°,  90°.  105°,  and  120°  West  Longitude.     Why  should  these 

meridians  be  chosen  as  the  central  meridians  for  our  time  belts?     


37 


Fig.  9.  —  Outline  Map  of  the  United  States. 


On  the  map  (Fig.  9)  sketch  in  the  four  standard  time  belts  of  the  United  States.    (See  Fig. 
556,  p.  404  of  Text-book.)     Why  are  the  actual  boundaries  irregular  and  not  on  the  meridians? 


In  which  of  the  standard  time  belts  do  you 


live? 


Where  and  how  much  would  you  change  your  watch  in  going  from  New  York  to  San  Francisco? 


From  Chicago  to  Boston  ? 


The  date  If  a  person  should  travel  completely  around  the  earth,  going  from  east  to  west,  how  many  times  (and 

line.  in  which  direction)  would  he  have  to  change  his  watch  if  he  made  the  change  every  fifteen  degrees  ? 


On  his  return  how  would  his  time  agree  with  that  of  his  starting  place  ? 


Would  he  have  gained  or  lost  a  day  ? 


What  would  be  the  case  in  traveling  around  the  earth  in  an  easterly  direction  ? 


38 


If  it  is  sunrise  Monday  where  you  live,  would  it  also  be  Monday  when  the  suu  next  rises  at  the  Hawaiian 

Islands?     In  China  ?    InLondon?     InNew 

York?     What  difficulty  does  this  bring  out  ?     


Where  does  Tuesday  begin  ? 


Where  would  you  begin  it  ? 


What  objections  would  there  be  to  choosing  a  meridian  running  through  a 

country  such  as  England,  or  Germany,  or  the  United  States  ?     


Fig.  10.  —  Map  of  World  for  plotting  the  International  Date  Line. 

39 


Such  a  line  would  be  called  a  date  line.    Find 

the    date    line  on  your  globe.     What  reason  can  you  suggest  for  locating  the  date  line  where  it  is  ? 


Does  the  date  line  follow  a  meridian  exactly  ?     Draw  in  the  date  line  on  the  map  of  the 

world  (Fig.  10).     If  you  crossed  that  line  Monday,  June  20,  coming  from  the  east,   what  would  be  the 

day  of  the  week  and  month  on  the  other  side  of  the  line  ? 

What  if  you    were    coming  from    the    west? 


Indicate  this  on  the  map,  showing  both  routes  by  arrows,  and  on  each  side  of  the  date  line  writing  the  days 
and  dates  going  each  way. 


4 


€ 


40 


Materials. 


Purpose. 


Local  ob- 
servations. 


IX. —THE   SEASONS 

For  Each  Student.  —  Desk  globe.    Cotton  string.     Colored  pencils.     (Method  of  using  string : 
Tie  tightly  around  globe  at  equator,  then  slip  over  globe  in  the  positions  indicated  below.) 

To  understand  how  the  earth's  revolution  around  the  sun,  together  with  the  inclination  of  the 
earth's  axis,  determines  seasons,  zones,  and  length  of  day  and  night. 

At  what  season  is  the  sun  highest  in  the  heavens  at  noon  where  you  live?     

At  what  season  lowest?     

At  what  two  opposite  seasons  is  the  sun  halfway  between  the  highest  and  lowest?     


%At  what  seasons  does  the  sun  rise  exactly  in  the  east  and  set  in  the  west  ? 


At  what  season  does 


it  rise  and  set  farthest  south  of  true  east  and  west  ? 


Farthest  north  of  true  east  and  west?     

In  a  few  sentences  write  a  description  of  the  changes  in  the  sun's  position  for  a  year. 


What  is  the  cause  of  these  changes  ? 


What  is  revolution? 


How  much  is  the  earth's  axis  inclined  ? 


Winter  Set  your  globe  on  the  desk  in  front  of  you  with  its  axis  inclined  23^-°,  and  with  the  north- 

season,  pole  end  pointed  away  from  you.    (Your  desk  globe  is  probably  set  at  this  inclination.)    Look  at 

the  globe  with  your  eyes  on  the  level  of  the  Tropic  of  Capricorn.     Can  you  see  the  south  pole  ? 

41 


The  north  pole  ?     If  you  held  a  lighted  candle  where  your 

eyes  were,  how  much  of  the  south  polar  region  would  be  lighted? 

Of  the  north  polar  region?     

Where,  on  the  surface  of  the  globe,  would  the  light  fall  most  directly? 

Place  the  string  around  the  globe  to  show  the  limits  of  the  lighted 

part  in  this  position.     To  what  latitude  does  it  extend  in  the  north? 

How  far  does  it  go  beyond  the  south  pole? 

Now  rotate  the  globe.     Under  these  conditions  is  there  any  night  in  the 

Antarctic  region  ?     Is  there  any  day  in  the  Arctic  region  ? 

Is  there  day  and  night  in  the  equatorial  region  ?    In  which  hemisphere  is  the 

period  of  daylight  longest  as  the  globe  rotates?     

Letting  the  globe  represent  the  earth,  and  the  light  the  sun,  in  which  hemisphere  is  the  sun* 

most  nearly  vertical?    Is  this  period  summer 

or  winter  at  your  home  ?  What  season  is  it  in  the  southern  hemisphere  ? 

Why  is  it  warmer  at  the  equator  than  in  the  Antarctic  region  ? 

Why  warmer  in  the  Antarctic  than  in  the  Arctic?     


Briefly  describe  the  changes  in  the  sun's  posi- 

tion,  and  length  of  day,  that  one  would  observe  in  passing  from  the  south  to  the  north  pole  at  this 
season. 


Summer  Swing  the  globe  around  to  the  desk  behind  you,  as  if  your  body  were  the  sun,  keeping  the 

season.  ax|s  always  inclined  in  the  same  direction.    Now  the  north  pole  points  toward  you.    With  your 

42 


eyes  at  the  same  level  as  when  you  looked  at  the  globe  in  the  winter  position,  what  part  of 
the  globe  is  directly  in  front  of  them?     

Again,  imagine  a  lighted  candle  placed  where  your  eyes  are ;  the  light  would  fall  most  directly 
on  the  Tropic  of  Cancer.  Place  the  string  around  the  globe  to  show  the  limits  of  the  part  that 
would  be  illuminated  if  a  strong  light  fell  upon  the  globe  when  in  this  position.     How  much 

of  the  north  polar  region  would  be  lighted? 

Of  the  south  polar  region  ?     Rotate  the  globe. 

Is  there  any  night  in  the  Arctic  region  ?   Is  there  any  day  in  the  Antarctic  ? 

What  parts  of  the  earth  have  day  and  night?     

* In  which  hemisphere  is  the 

period  of  daylight  longest  as  the  globe  rotates  ?     

Letting  the  globe  represent  the  earth,  and  the  light  the  sun,  in  which  hemisphere  is  the  sun 

most  nearly  vertical  at  this  season  ?     What 

season  does  this  represent  in  the  northern  hemisphere  ? In  the 

southern?    . Why  is  it  warm  at  the  equator ?    

Why  is  there  no  winter 

there?     

In  which  direction  will  a  shadow  fall  at  the  equator  at  noon?     

At  the  Tropic  of  Cancer?     

At  the  Arctic  circle  ?  _' At  the  Tropic  of  Capri- 
corn?          Where  will  the  shadow  be  longest? 

Explain   why  the   sun   rises   and   sets   farther   north   at   this   season   than   in  the   winter. 


Briefly  describe  the  changes  in  the  sun's  position  and  the  length  of  day  that  one  would 
observe  in  passing  from  the  north  to  the  south  pole  at  this  season.     


43 


Spring  and  Swing  the  globe  around  to  the  desk  on  your  left,  with  the  axis  still  pointing  as  before. 

autumn.        This  will  represent  March  21.     With  your  eye  at  the  same  level  as  before,  you  now  look 

directly  at  the  equator.     Place  the  string  on  the  globe  to  show  the  area  lighted  in  this 

position.     What  part  of  the  surface  must  then  receive  vertical  sun's  rays  ? 

Does  the  north  pole  receive  sunlight  in  this  position  ? 

The  south  pole  ?   In  what  proportions  does  the  string  divide 

the  equator?     

Kotate  the  globe.     How   many   hours   of   sunlight   would   a   place   on   the   equator   have  ? 

Therefore,  how  many  hours  of  night?     

Does  the  string  divide  other  parallels  equally?     At  this  period,  how  long  is 

the  day  and  night  in  all  parts  of  the  earth?     Why  is  this  called  the 

spring  equinox  ?    . 

Does  the  sun  also  rise  and  set  in  the  Arctic  and  Antarctic  regions  at  this 

season  ?     How  does  the  sun  appear  at  the  poles  themselves  ?     

Swing  the  globe  around  to  the  desk  on  your  right,  with  the  axis  still  pointing  as  before. 
Answer  the  same  questions  as  for  the  last  position.     


Why  should  this  period  (Sept.  23)  be 
44 


called  the  autumnal  equinox  ? 


By  placing  the  globe  in  other  positions,  show  that  there  is 

no  other  season  besides  autumn  and  spring  when  the  days  and  nights  are  equal  all  over  the 

earth.     Where  would  they  be  equal  on  Dec.  21  ?     

On  June  21?    : 


Make  a  drawing  (see  Fig.  553,  p.  401,  in  Text-book)  to  show  the  revolution  of  the  earth  about  the  sun, 
fixing  the  position  for  June  21,  Sept.  23,  Dec.  21,  and  March  21,  and  shade  the  half  of  the  globe  to  represent 
night  at  each  of  these  dates. 


The  zones.            What  reason  can  you  give  for  placing  the   Tropic  of  Cancer,  Tropic  of  Capricorn, 
Arctic   Circle,    and    Antarctic   Circle   where   they   are?     

What  is  the  latitude  of  each? 


45 


What  reasons   can  you   give   for  the   fact   that  the  torrid  zone  is  warm  at  all  seasons? 


For  the  fact  that  the  temperate  zones  have  warm  summers  and  cold  winters  ? 


For  the  fact  that  the  frigid  zones  are  cold  even  in  summer? 


On  the  outline  map  (Fig.  11)  sketch  in  the  five  zones  with  different  colored  pencils,  and  write 
in  their  names.     Why  would  you  not  expect  to  find  an  abrupt  change  in  going  from  one  zone 


to  the  next? 


To  find  Place  the  string  on  the  globe  in  the  position  of  the  equinox.     What  is  the  number  of  degrees  of  longi- 

the  length 
of  day  and 
night. 


tude  on  the  lighted  side  at  the  equator  ?     „__.     At  45°  ?     

At  60°  ?    Remembering  that  15°  of  longitude  represents  one  hour  of  time,  how 

many    hours    long    is    the    day    at    the    equinox  ?     

The  night?     Shift  the  string  to  the  position  of  midwinter 

(Dec.  21).     How  many  degrees  are  lighted  at  the  equator  ?     At  the  Tropic  of 

Capricorn?    At  45°  N.  latitude ? At  45°  S.  latitude ? 

At  your  own  home  ?     

What  is  the  length  of  daylight  at  each  of  these  parts  of  the  earth  en  Dec.  21  ?    , 


summer  position  (June  21)  make  the  same  observations  for  that  date. 

46 


..     With  the  string  in  the  mid- 


♦ 


:priy7¥ 


•> 


4i_ 


-Sii 


SB} 
w  H   m 


47 


♦ 


48 


Materials. 


Purpose. 


Introduc- 
tory. 


The  rock 
outcrop. 


AUTUMN   FIELD   WORK 
X.  — FIELD   EXCURSION   FOR   COLLECTION   OF    SPECIMENS 

For  Each  Student.  —  A  bag,  or  small  basket,  for  carrying  specimens. 

For  General  Class  Use.  —  One  or  more  hammers. 

To  collect  specimens  (such  as  minerals,  rocks,  and  fossils),'  for  later  study  in  the  laboratory  ; 
to  gain  a  knowledge  of  the  nature  and  characteristics  of  the  bed  rock  ;  and  to  study  the  soil. 

For  this  excursion  select  the  nearest  rock  outcrop  within  easy  reach ;  and,  if  possible,  on 
the  way  to  it  examine  one  or  more  bowlders.  If  different  rock  outcrops  are  accessible  on  this 
excursion,  examine  several. 

Describe  the  appearance  of  the  outcrop      


Was  it  revealed  by  the  work  of  man,  or  of 

water,  or  is  it  a  hillside  ledge  with  no  soil  on  it?     

. . What  is  the  color  of  the  rock?     

Is  it  hard  or  soft  ?     (Try  the  effect  of  a  hammer  or 

knife  on  it.) Is  its  texture  coarse  or  fine- 
grained?         Can  you  see  individual  minerals  in  it? 

If  so,  describe  their  appearance.     


Is  the  rock  in  layers  or  not  ?     If  in  layers,  what  differences  are  there 

between  them?     


• 


Are  the  layers  horizontal  or  inclined  ? 


49 


Are  there  any  fossils?     If  so,  collect  specimens.     After  the  teacher 

has  told  you  what  a  sedimentary  rock  is,  tell  whether  this  is  a  sedimentary  or  a  crystalline 

rock.      How  is  a  sedimentary  rock  distin- 
guished from  a  crystalline  rock? 


There  are  many  kinds  of  sedimentary  and  crystalline 

rocks.     The  teacher  will  tell  you  the  name  of  this  one.     Write  a  brief  description  of  it. 


Collect  a  specimen  for  study  in  the  laboratory  when  you  are  studying  minerals  and  rocks. 
When  a  rock  is  subjected  to  strain,  as  is  often  the  case  in  the  earth's  crust,  it  breaks, 

forming  a  parting  called  a  joint  plane.     Are  there  joint  planes  in  the  outcrop  ? 

Write  down  any  other  observations  you  make,  or  any  facts  that  the  teacher  tells  you  about 
this  outcrop.     


Soils.  Is  there  soil  resting  on  the  rock  outcrop?     Examine  and  describe  it, 

stating  whether  it  is  coarse  or  fine    ;     whether  it  is  different  at  the 

top  and  bottom     

50 


;     whether  it  has  pebbles  in  it  or  not     ; 

whether  it  grades  down  into  the  rock  or  is  separated  sharply  from  it     

;    and  any  other  observations 

you  may  make.     


Other  On  your  way  from  the  outcrop  watch  carefully  for  bowlders  and  pebbles.     Do  you  find 

minerals 

and  rocks.     any?     Are  they  like  the  rock  in  the  outcrop ?     .__: If  not,  collect 

specimens  for  study  in  the  laboratory. 


51 


Materials. 


Purpose. 


Introduc- 
tory. 


Effect  of 
expansion 
and  con- 
traction. 


XI. —EXCURSION  FOR   THE   STUDY   OF   WEATHERING 

For  Each  Student.  —  A  small  bag  or  basket  for  the  collection  of  specimens. 
For  General  Class  Use.  —  One  or  more  hammers. 

To  study  in  the  field  some  of  the  processes  by  which  rocks  are  disintegrated  or  broken  down  on 
exposure  to  air. 

The  class  should  be  taken  to  some  rock  outcrop,  or  failing  that,  to  a  bowlder.  If  several 
outcrops  are  available,  select  the  one  at  which  it  is  possible  to  answer  the  largest  number  of 
the  following  questions.  Almost  any  outcrop  will  furnish  opportunity  to  make  some  observa- 
tions on  weathering. 

Is   the   rock   of  this   outcrop   composed   of   one    or    of    several    kinds    of    minerals? 

Heat  causes  minerals  to  expand,  and  they 

contract  when  cooled.     Different  minerals  expand  and  contract  at  different  rates.     As  this 
outcrop  is  warmed  in  the  day  and  cooled  at  night,  what  must  be  the  changes  in  the  rock  as  a 

whole  ?     

What  must  happen  as  a  result  of  the  strains  at  the  junction  of  minerals  of  different  kinds  ? 


State  briefly  how  changes  in  temperature  aid  in  the  disruption  of  rocks  where  they  outcrop. 


Effect  of 
frost. 


Are  there  any  visible  cracks  in  the  rocks?     When  might  water  enter  the 

rocks?     

Does  water  expand  or  contract  on  freezing?     

When  the  cracks  are  filled  with  water  and  the  temperature  falls  below  freezing  point,  what  is 


the  effect  of  the  freezing  of  the  water  in  the  cracks  ? 


Are  there  other  smaller  cracks  in  the 


53 


rock,  —  for  instance,  between  the  mineral  grains?     What  influence  do 

these  have  in  aiding  in  the  breaking  up  of  the  rock?     

Write  a  brief  paragraph  stating  the 

effect  of  frost  in  rock  disintegration. 


Effect  of  Are  there  any  lichens  on  the  outcrop ?     ■...     How  do  they  cling  to  the  rock? 

plants. 


As  the  lichens  grow,  how  do  they  aid  in  rock  disintegration?     

. Are  there  any  bushes  or 

trees  sending  their  roots  down  into  the  rock  ?      What  effect  will  the 

growth  of  these  roots  have  on  the  rock?     


Solution.  As  the  rain  water  passes  through  the  soil   it   takes  with  it  certain  substances  (like 

carbon  dioxide  and  humic  acids)  supplied  by  plant  decay.     The  water  then  has  power  to 
dissolve  some  minerals.     Where,  in   this  rock  outcrop,  will  water  percolate  most  freely? 


If  it  flows  along   a  joint   plane,   what   effect   will   it  have   on   the   rock   on   either  side? 

If  it   slowly   percolates   between   the   mineral  grains,  what  effect  will  it  have  on  them? 

State  how  the  work  of  solution  aids  rocks  in  crumbling.     

54 


Have  you  ever  seen  an  iron  spring,  or  a  sulphur  spring,  or  other  kind  of  mineral  spring? 


Why  are  such  springs  called  mineral  springs  ?     

How  did  the  water  obtain  its  load  of  dis- 
solved mineral  ?      

"Hard  water"  is  water  with  mineral  matter  in  solution.     How  did  this  get  in  solution? 


Decay  of  Percolating  water  not  only  dissolves  some  minerals,  but  it  causes  some  to  change  greatly, 

rocks.  as  iron  is  caused  to  change  to  rust.     Break  off  a  piece  of  the  rock  to  see  whether  any  of  the 

minerals  show  such  a  change.     Describe  the  difference  between  the  outer  and  inner  parts  of 


the  piece  of  rock. 


Are  any  of  the  minerals  rusted  red  or  yellow  on  the  outside?     Are 

any  of  them  changed  to  dull  whitish  color?     If  one  kind  of  a  min- 
eral in  a  rock  decays,  and  the  other  does  not,  how  does  that  weaken  the  rock  as  a  whole? 


State  briefly  how  decay  results  in  rock  disintegration. 


55 


Make  a  list  of  the  agencies  of  weathering  that  yon  have  observed  at  this  outcrop. 


Add  to  the  list  any  other  agencies  of  weathering  that  you  know  about,  but  have  not  observed. 


What  As  the  rock  of  this  outcrop  disintegrates,  what  becomes  of  the  fragments?     

becomes 
of  the  dis- 
integrated 
rock. 

Do  any  fall 

to  the  base  of  the  cliff,  forming  a  talus?     Describe  the  talus  and  ex- 
plain its  formation.     


Are  any  of  the  fragments  carried  off  by  streams? 

Are  any  taken  away  by  plants  ?     How  ?     


What  becomes  of  the  dissolved 

mineral?     

Make  a  brief  statement  to  show  what  becomes  of  the  products  of  rock  weathering. 


56 


The  forma-  If  the  slope  of  the  bedrock  is  so  gentle  that  the  products  of  weathering  are   not  all 

tion  of  soil,   removed,  a  mantle  of  soil  is  formed,  called  a  residual  soil.     How  would  such  a  soil  differ  in 

character  from  the  surface  to  the  bedrock?     


t) 


How  would  the  roots  of  plants  aid  in  making  the  soil  finer  ? 


What  effect  would  earthworms  have  on  the  texture  of  the  soil? 


Why  would  a  residual  soil 

be  different  on  different  kinds  of  rocks,  such  as  limestone,  slate,  and  granite ? 


Would  a  resid- 
ual soil  grade  into  the  bedrock,  or  would  there  be  a  sharp  line  separating  them? 

., What  is  the 

nature  of  the  soil  on  this  outcrop?     Describe  it. 


Is  it  a  residual  soil  ?     

57 


Other  ob-  Write  down  any  other  observations  you  have  made  on  this  excursion,  or  any  other  facts 

servations.    yQu  kave  leaded,     if  y0U  have  ever  noted  the  effect  of  weathering  elsewhere,  as  on  bowlders, 
or  on  stone  buildings,  or  on  the  headstones  in  cemeteries,  state  what  you  have  observed. 


58 


9 


XII.  — EXCURSION   TO   STUDY  STREAM   WORK 

Purpose.  To  study  the  work  of  streams  in  eroding  their  valleys  and  forming  deposits. 

Introduc-  The  banks  of  a  comparatively  small  stream  whose  current  is  alternately  swift  and  slug- 

tory.  gish  will  best  serve  the  purpose  of  this  excursion.     Any  water  course  will,  however,  give  an 

opportunity  for  profitable  work,  even  though  some  of  the  observations  outlined  cannot  be  made. 

Failing  a  perennial  stream,  the  course  of  a  wet-weather  stream  along  a  roadside  or  elsewhere 

will  afford  many  illustrations  of  stream  processes. 

Transpor-  Is  the  water   clear  or  cloudy?     If  it  is 

tation  of 

sediment.      not  c]earj  what  causes  the  cloudiness?     


t) 


.__ How  are  clay  and  other  fine  earthy  particles  carried 

along  by  the  current?    

What  is  the  nature  of  the  bottom  of  the  channel  at  this  point? 


Was  the  material  of  which  it  is  composed  brought  by  the  current?     If  so, 

was  the  current  faster  or  slower  at  the  time  when  the  material  was  deposited  ?     

How  do  you  know  this  ?     


If  the  stream  is  flowing  over  bedrock,  what  does  this  fact  indicate  as  to  the  transporting 
power  of  the  stream  at  this  point? 


59 


Examine,  if  possible,  a  place  in  the  stream  course  where  the  water  is  shallow  and  flowing 
rapidly.     What  kind  (as  to  size  and  nature)  of  particles  are  being  rolled  along  on  the  bottom? 


Throw  pebbles,  sand,  and  clay  into  the  current  to  see  how  coarse  material  can  be  transported. 


Would  larger  or  smaller  particles  be  moved  at  flood  times  ? 
Why?     


What  evidence  of  this  is  afforded  by  the  bowlders  and  pebbles  in  the  bed  of  the  stream  at 
different  points  in  its  course  ?     


When  may  they  be  moved  again  ? 


Erosional  Have  the  bowlders  and  pebbles  in  the  stream  bed  rounded  or  sharp  corners  ? 

work  of 

streams.  Why? 


What  does  this  indicate  as  to  the  way  in  which  the  material  of  a  bowlder  or  pebble  will 
eventually  reach  the  sea? 


60 


• 


What  will  be  the  effect  on  the  bedrock  as  the  pebbles  and  bowlders  are  rolled  over  it  ? 


What  effect  will  the  transportation  of  sand  particles  have  ? 


What  will  be  the  effect,  in  both  cases,  on  the  depth  of  the  stream  channel  ? 


What  is  the  source  of  the  material  which  the  stream  carries '/ 


How  does  weathering  assist  the  stream  in  securing  this  material  ? 


How  are  stream  valleys  deepened  ? 


Is  the  course  of  the  stream  a  straight  line  ? 
What  is  meant  by  a  meandering  course  ?     


61 


What  work  is  the  current  doing  where  it  swings  toward   the  bank   in   a  meander  curve? 


What  effect  will  this  have  on  the  width  of  its  channel  ? 


How  does  weathering  aid  in  the  widening  of  stream  channels  ? 


What  illustrations  of  this  do  you  find  here  ? 


Why  have  ripraps  and  embankments  been  built  by  man  along  many  streams  ? 


Deposition  Where  are  bars  formed  in  the  stream's  course  ? 

of  sedi- 
ment. 


.  .Of  what  materials  are  they  composed  ? 


62 


How  do  you  account  for  their  presence  and  composition  in  each  case  noted  ? 


When  will  this  material  be  moved  again  ? 


Where  will  it  ultimately  be  deposited  ? 


Is  sediment  carried  in  one  continuous  journey  from  its  starting  place  to  the  sea? 
Describe    the    process.      


What  forms  may  the  material  take  when  deposited  in  the  sea  or  a  lake  ? 


What  illustrations  of 

this  do  you  find  in  the  small  pools  or  ponds  in  the  stream  course? 


63 


OF   THE 

UNIVERSITY 

OF 


Write  a  short  paragraph  summarizing  the  work  of  streams  in  deepening  and  widening 
their  valleys  and  in  forming  sedimentary  deposits. 


♦ 


64 


• 


XIII.  — EXCURSION  TO   LAKE   OR   SEA   COAST 

Purpose.  To  study  the  waves  and  currents  on  a  coast  line;  to  note  their  importance  in  erosion,  trans- 

portation, and  deposition;  and  to  study  some  of  the  land  forms  resulting  from  their  action. 

Introduc-  Even  the  shore  of  a  very  small  pond  will  often  illustrate  the  main  phenomena  which  it  is 

tory-  the  purpose  of  this  excursion  to  study ;  therefore,  if  a  large  lake  or  a  sea  coast  are  not  access- 

ible, this  excursion  may  nevertheless  be  undertaken  with  profit. 

The  wave.  Are  there  any  waves  on  the  water  surface  ?     About  how  high  are  they  ? 

What  is  the  cause  of  the  waves?     


At  what  time  are  the  waves  higher  than  now? 


As  the  waves  approach  the  coast,  how  do  they  change  in  form ' 


Are  there  points  where  the  waves  reach  the  coast  with  greater  vigor  than  others  ? 
What  reason  can  you  give  for  their  greater  vigor  in  such  places?     


Currents.  Is  there  a  tide  on  this  coast  ?      If  so,  describe  it. 


Does  the  tide  cause  currents  in  any  place?     When  the  wind  blows  steadily 

over  a  body  of  water,  what  other  movement  of  the  water  is  there  besides  that  of  the  waves? 


65 


Is  a  wind-formed  current  a  rapid  or  a  slow  movement  ?     

How  does  such  a  current  compare  in  power  Avith  the  waves  ? 


Can  it  transport  coarse  sediment? Clay?  •_ 

Wave  work           Do  the  waves  beat  against  a  headland  at  any  point  on  this  coast  ? 
on  head- 
lands. jg  ^  headland  hard  rock  or  unconsolidated  material  ?      


Is  it  steep  or  gently  sloping?     What  evidence 

is  there  that  the  waves  are  working  to  erode  the  headland?     


How  does  weathering  assist  in  the  work? 


If  this  work  of  erosion  continues,  what  change  will  take  place  in  the  form  and  position  of  the 
headland?      1 


Is  such  work  most  rapid  in  consolidated  or  in  unconsolidated  material?     

As  weathering  and  wave  erosion  remove  material, 

what  becomes  of  the  fragments?     


Wave  work  Of  what  is  the  beach  made?      

on  beaches. 

As  the  waves  wash  up  on  the  beach,  what  size 

material — clay,  sand,  or  pebbles — do  they  move?     

What  size  material  can  the  waves  move  in  times  of  storm?      . 


66 


What  relation,  if  any,  is  there  between  the  beach  material  and  the  headlands  ? 


How  was  the  beach  material  brought  to  its  present  position  ? 


As  the  waves  move  the  beach  material   about,  what  change  in  size  of   particles  results? 

Where  are  the  finer  particles,  such  as  clay,  carried?     

How  do  the  wind-formed  currents  aid  in  this 

transportation?    

The  undertow?     

How  does  such  transportation  aid  in  explaining  the  absence  of  clay  beaches?      

In   explaining  the   frequency   of   clay   deposits   in  protected   bays   where   currents   enter? 
In  explaining  the  fact  that  clay  often  covers  the  bottom  at  a  short  distance  from  the  beach? 


Animal  and  Are  there  any  animals  or  plants  living  in  the  zone  reached  by  the  waves  ? 

plant  life. 

What  kinds?    


Do  they  aid  or  retard  the  work  of  the  waves  or  currents  in  any  way  ? 


^|ther  What  other  phenomena  are  illustrated  on  this  coast  ? 

■^Reserva- 
tions. 

67 


Does  ice,  for  instance,  ever  form  here;  and  what  effect  does  it  have? 


Is  the  coast  line  a  place  of  rapid  or  slow  change? 


Are  there  ripple  marks?     Study  their  formation  and  explain  them. 


State  any  observations   you   may  make   on   the  work  of  the  wind  in   drifting  sand  about. 


What  observations  have  you  ever  made  on  other  coasts  than  this  one  ? 


68 


• 


Form  of  the  Is  the  coastline  straight  or  irregular?    Is  it  a  raised  or  a  lowered  coast? 

coastline. 

Have  the  waves  and  currents  produced  much 

or  little  change  on  this  coast? 


Are  they  now  causing  much  or  little  change  ? 


Briefly  describe  the  coast  as  you  have  observed  it;  state  how  the  agencies  of  denudation 
are  modifying  it,  and  explain  its  present  form  so  far  as  the  facts  you  have  seen  enable  you  to 

do  so.     


69 


♦ 


Materials. 


Purpose. 


Introduc- 
tory. 


Method  of 
study. 

Color. 


Hardness. 


MINERALS,   ROCKS,  AND   SOIL 

XIV.— PROPERTIES   OF   MINERALS 

For  Each  Student.  —  Fragments  of  quartz  crystal,  feldspar,  hornblende,  halite  (salt), 
biotite  mica,  calcite,  gypsum.     Steel  knife  or  scratch  point.     Window  glass  (fragment). 

For  General  Class  Use.  —  Dilute  hydrochloric  acid,  and  several  glass  stirring  rods ;  or 
acid- dropping  bottles. 

To  learn  the  properties  by  means  of  which  the  more  common  minerals  may  be  identified  and 
distinguished. 

A  mineral  may  be  defined  (in  general  terms)  as  any  inorganic  solid,  formed  in  nature, 
which  is  composed  of  certain  elements  in  definite  combinations.  The  nature  of  the  elements, 
the  amounts  of  each  present,  and  the  way  they  are  combined  give  each  mineral  its  own  pecu- 
liar characteristics.  Thus  a  mineral  is  a  naturally  formed  solid  which  has  the  same  composi- 
tion and  structure  throughout  its  mass. 

Number  your  specimens  from  1  to  7.  Then  make  the  observations  as  directed  below 
and  record  the  results.     Refer  to  each  specimen  by  the  number  you  have  given  it. 

Which  specimens   are  light  colored?     

Which  are  dark?     What  is  the  color  of  No.  1? 

Of  No.  2?     No.  3? 

No.  4?    No.  5?     No.  6? 

No.  7?    

If  one  mineral  scratches  another,  which  is  the  harder,  the  one  scratched  or  the  one  used 
to  scratch  with?     


• 


Number  of 
Specimen 

Numbers  of  Specimens 
which  it  scratches 

Numbers  of  Specimens 
which  scratch  it 

By  using  a  sharp  point  or  corner  of  each 
specimen  to  scratch  with,  and  selecting  a  flat 
place  to  scratch  on,  try  to  scratch  each  mineral 
with  every  other  one  and  set  down  your  ob- 
servations in  the  table  opposite.  Be  careful 
not  to  press  so  hard  as  to  break  off  the  points 
by  mere  weight. 


71 


Cleavage ; 
and  crystal- 
line or 
amorphous 
form. 


Resume. 


Observa- 
tions on 
crystal 
faces  and 
cleavage 
planes. 


Which  of  the  seven  is  the  hardest  specimen?     Which  is  the  softest? 

Arrange  the  specimens  in  the  order  of  their  hardness,  putting  the  hardest 


first. 


Hardest 

Next  Hardest 

Third  Hardest 

Fourth  Hardest 

Fifth  Hardest 

Sixth  Hardest 

Softest  ' 

Which  numbers   can  you   scratch   with   your   finger  nail? 
Which  with  a  piece  of  steel   or  glass?     


Many  minerals  break  more  readily  in  certain  directions  than  in  others,  thus  giving  these 
minerals  the  property  of  cleavage.  The  smooth  planes  along  which  these  breaks  occur  are 
called  cleavage  planes.     In  other  directions  the  mineral  breaks  with  a  rough  or  uneven  surface. 

Not  all  smooth  faces  seen  in  minerals  are  cleavage  planes.  If  a  mineral  is  built  up  under 
proper  conditions,  and  is  free  to  grow  in  all  directions,  it  takes  a  definite  form  known  as  its 
crystal  form.     Such  minerals  have  smooth  outside  faces,  called  crystal  faces. 

Cleavage  planes  and  crystal  faces  can  be  distinguished  by  the  fact  that  cleavage  planes 
repeat  themselves,  one  parallel  to  the  other,  while  crystal  faces  simply  bound  the  outside  of 
the  crystal. 

If  the  proper  conditions  are  not  present  when  a  mineral  is  forming,  it  will  not  become  a 
crystal  but  will  appear  as  a  lump  of  the  substance  without  definite  form.  Such  a  mineral  is 
said  to  be  amorphous,  a  word  meaning  "without  form."  Minerals  in  the  amorphous  state 
have  neither  crystal  faces  nor  cleavage  planes. 

Minerals  are  either  crystalline  or  amorphous.  Complete  crystals  of  minerals  have  smooth 
crystal  faces.  Parts  of  crystals  may  or  may  not  show  smooth  cleavage  planes.  The  presence 
of  a  cleavage  plane  indicates  that  the  mineral  will  split  in  that  direction,  with  a- smooth  face, 
as  finely  as  it  can  be  divided.  Not  all  crystalline  minerals  have  cleavage  planes,  while  some 
have  them  in  a  number  of  directions.     Amorphous  minerals  have  no  smooth  faces. 

Which  of  your  specimens  have  crystal  faces  or  crystal  form  ?     

Which  have  cleavage  planes? 

Which    have   cleavage  planes  in  more  than   one    direction?     

How    many    of    them     have    cleavages    at    right   angles    to 

each  other?     How  many  at  inclined  angles 

to  each  other?     Which  of   your   specimens 

are  amorphous?     


Suggested  Growing  crystals.  —  Dissolve  as  much  salt  as  possible  in  a  glass  of  hot  water.     Suspend  a  cotton  string 
home  work  so  that  its  free  end  will  extend  below  the  surface  of  the  solution.     Allow  the  solution  to  cool  as  slowly  as 
for  stu- 
dents,            possible.     Note  the  results.      


72 


• 


Try  this  also  with  a  solution  of  sugar.     Of  alum.    Is  there  any  difference  in  the  form  of  the  crystals  ? 
Try  the  effect  of  cooling  a  salt  solution  rapidly. 


Make  a  cold  solution   of  either 

sugar  or  alum  and  allow  it  to  evaporate  slowly.     Why  should  these  crystals  be  so  much  larger  and  more 


perfect  than  the  others  ? 


Luster.  The  manner  in  which  light  is  reflected  from  a  mineral  gives  it  an  appearance  that  is 

termed  its  luster.  Thus  from  some  minerals  the  light  is  reflected  so  that  it  appears  like  a 
glassy  surface.  Such  a  mineral  is  said  to  have  a  glassy  luster.  Others  have  pearly,  metallic, 
oily,  earthy,  etc.,  lusters.  Describe  in  these  terms  the  luster  of  each  of  your  specimens,  and 
set  down  in  the  table. 


Acid  test. 


• 


Specimkn 
Number 

Luster 

Name  of  Specimen* 

1 

< 

2 

3 

4 

5 

». 

6 

7 

Have  the  teacher  tell  you  the  name  of  each  of  your  specimens  and  set  it  down  in  the  third 
column  above,  opposite  its  number. 

Apply  a  drop  of  acid  to  each  of  your  specimens.     If  any  of  them  begin  to  bubble,  you 
have   a  chemical   reaction ;   that   is,  the  mineral  is   changed   by  the  acid.      Which  of  the 


minerals  shows  such  a  reaction  ? 


73 


XV.  — COMMON   ROCK-FORMING   MINERALS 

Materials.  For  Each  Student.  — Specimens  of  quartz,  orthoclase  feldspar,  plagioclase  feldspar,  muscovite 

mica,  biotite  mica,  hornblende,  iron  pyrites  or  pyrite,  calcite,  dolomite.     Steel  scratcher. 

For  General  Class  Use.  —  If  possible  have  large  crystal  specimens  of  the  different  minerals 
named  above  for  examination  by  the  class.     Hydrochloric  acid  and  stirring  rods. 

Purpose.  To  learn  the  properties  of  the  common  rock-forming  minerals. 

Introduc-  On  the  following  page  is  a  table  with  a  column  for  each  specimen  named  above.     Deter- 

tory«  mine  the  characteristics  of  each  mineral  and  set  down  your  observations  in  the  proper  place, 

as  indicated.  The  chemical  composition  of  each  is  given  by  its  chemical  symbol  and  is  also 
(in  general  terms)  written  out.  The  teacher  will  describe  those  elements  mentioned  with 
which  you  are  not  familiar.  These  minerals  are  the  ones  which  make  up  the  bulk  of  the 
rock  masses  of  the  earth.  Hardness  is  to  be  stated  in  terms  of  harder  than  steel,  harder  than 
a  finger  nail,  softer  than  a  finger  nail. 

How  many  of  the  minerals   have  oxygen?     How  many  have 

silicon  ?     What   does  this  indicate  as  to   the  abundance  of  these 

elements  in  the  earth's  crust?     

How  many  different  elements  are  present  in  all  the  min- 
erals in  your  list  ?     


75 


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Materials. 


Purpose. 
Method  and 


XVI.— SOME  OF  THE  MOST  COMMON  ECONOMIC  MINERALS 

For  Each  Student.  —  Specimens  of  hematite,  magnetite,  halite,  gypsum.    Steel  scratcher. 

For  General  Class  Use. — If  possible,  some  specimens  of  limonite,  magnetite,  gold,  silver,  copper, 
lead,  and  zinc  ores.  (In  some  localities  the  teacher  may  find  it  desirable  to  have  these  minerals  for 
each  student.)    Hydrochloric  acid  and  glass  stirring  rods.  . 

To  learn  the  characteristics  of  a  few  important  economic  minerals. 


Make  observations  and  describe  each  of  the  above  minerals  ;  putting  the  description  of 
results.  each  in  the  form  of  a  sentence,  as  below. 

Hematite  (Fe  and  0)  has  a color  ;  a  hardness 

;    crystal  faces  are 

(or  are  not)  present;    cleavage  planes  are  (or  are 

not)  present;  these  are  at angles  to  each  other ; 

its  luster  is     ;  and  it  does  (or  does  not)  respond  to  the  acid  test.     It 

is  used  as  a  source  of    


Magnetite  (FeO) 


• 


Halite  (NaCl)  (CI  =  Chlorine) 


77 


Gypsum  (CaSO<  +  H20) 


Examine  the  specimens  (if  any)  which  the  teacher  distributes  and  set  down  the  most  striking 
characteristic  of  each. 


78 


• 


XVII.— COMPARISON  OF  CHARACTERISTICS  OF  COMMON  MINERALS 

Materials.  For  Each  Student. — The    specimens   of   the  rock-forming  and   economic  minerals  previously 

studied. 

Purpose.  To  learn  to  distinguish  between  minerals  having  simUar  properties. 

Refer  to  the  table  of  properties  you  have  already  made,  and  reexamine  the  specimens. 

Comparison  In  what  characteristics  do  quartz  and  feldspar  resemble  each  other? 

of  minerals. 

,    How  can  they  be 

told  apart  ? 

Examine  the  cleavage  faces  of  the  orthoclase  and  the  plagioclase 

feldspar.    Which  kind  has  the  fine  parallel  lines  ? i . 

How  do  the  two  micas  differ  in  color  ?    

Would  the  fact  that  iron  is  present  in  the  biotite  sug- 
gest any  explanation  for  this  ?   

In  what  properties  does  hornblende  resemble  the  feldspars? 

In  which  does  it  differ  ?  


Is  its  cleavage  as  easy  to  see  as  that  of  the  feldspars?. 

How  may  hornblende  and  mica  be  distinguished?     


How  would  you  most  quickly  recognize  pyrite  ? 

. What  resemblances  have  calcite  and  dolomite? 


79 


How  may  they  be  distinguished  from  each  other  ?    

In  what  ways  does  halite  resemble  quartz? 

Taste  both.     What  is  the  result? 

What  would  happen  to  halite  if  it  were  present  near  the 

surface  of  the  earth  in  a  humid  climate  ?  

How  could  you  most  readily  identify  hematite  ? 

What  is  the  most  noticeable  property   of 

gypsum? _ 


♦ 


80 


• 


Materials. 


Purpose. 

Igneous 
rocks. 


XVIII.  —  GENERAL   CLASSIFICATION   OF   ROCKS 

For  Each  Student.  —  Specimen  of  granite,  sandstone,  fossiliferous  limestone,  schist.     Fine- 
pointed  steel  scratcher,  or  knife  point. 

For  General  Class  Use.  —  Hydrochloric  acid  and  glass  stirring  rods. 

To  learn  the  cfiaracteristics  of  the  four  great  classes  of  rocks. 

Examine  your  specimen  of  granite.     Of  how  many  different  minerals  is  it  composed  ? 

Are  the  minerals  crystalline  or  amorphous  ?     

Identify  each  mineral,  and  make  a  list  of  them  in  the  order  of  importance  as  to  amount  present. 


How  are  the  minerals  arranged  with  respect  to  one  another  ? 


This  kind  of  rock  is  known  as  an  Igneous  (=  Fire)  Bock  because  of  the  fact  that  it  is  formed  by  the 
cooling  of  a  hot  molten  mass  of  rock  magma  which  rises  from  within  the  earth.  If  such  a  molten  mass  cools 
slowly,  the  minerals  can  separate  out  into  crystal  grains  of  good  size,  as  in  the  granite  you  have  examined  ;  if 
they  cool  very  quickly,  the  rock  which  results  is  like  a  black  glass,  or  furnace  slag.  There  are  all  gradations 
between  these  two  extremes.  Then  again,  the  molten  magmas  are  of  different  composition  ;  some  have 
elements  that  others  lack.    Consequently,  minerals  that  are  present  in  one  igneous  rock  may  be  absent  in  others. 


Sedimen- 
tary rocks. 


What  mineral  composes  the  bulk  of  your  sandstone  specimen?     

Are  other  minerals  visible?      If  so,  what  proportion  of  the  mass  do  they 

form  ? 


Eub  your  finger  (or  a  knife)  with  some  pressure  over  the  surface  of  the  specimen.    What  is  the 
shape  of  the  particles  you  break  off? 


What  differences  do  you  see  between  the  sandstone 


and  the  granite  ? 


81 


Sandstone  is  a  Sedimentary  Bock ;  that  is,  it  is  one  of  the  great  class  of  rocks  which  are  formed  by 
deposition,  generally  in  water.  The  material,  or  sediment,  of  which  they  are  composed,  is  usually  brought  by 
streams  which  have  gathered  it  along  their  courses  and  carried  it  in  their  currents  to  their  mouths,  where  they 
must  deposit  it,  because  the  current  ceases.  Sedimentary  rocks  are  all  alike  in  the  fact  that  they  have  been 
formed  by  deposit  from  a  current,  usually  a  water  current ;  but  wind,  for  example,  may  also  act  as  a  carrier 
and  depositor  of  sediment. 

Organic  What  traces  of  animal  life  does  your  limestone  specimen  show  ?     

rocks. 


Where  do  such  animals 

live?       

What  becomes  of  their  shells  when  they  die  ?     

Does  the  acid  affect  this  rock?     How  might  such  a  rock  be  formed? 


Limestone  such  as  this  is  an  Organic  Bock.  Organic  limestones,  however,  grade  into  those  which  have 
formed  chemically  (as  a  deposit  of  salt  would  form  in  a  glass  if  you  dried  up  a  salt  solution) .  When  limestones 
are  chemically  formed,  they  are  generally  classed  with  the  sedimentary  rocks. 

Metamor-  Of  what  minerals  is  your  schist  specimen  composed? 

phic  rocks. 

How    are    these    arranged? 


How  does  this  affect  the  rock's  strength? 

Why  is  it  not  as  strong  as  a  granite?. 


82 


• 


Along  the  lines  of  what  mineral  does  it  break  most  readily  ? 
.  Why?  


Schist  is  one  of  the  great  class  of  Metamorphic  (changed)  Bocks.  Originally  they  were  igneous,  sedi- 
mentary, or  organic  rocks ;  but  later  they  were  heated  and  compressed  in  the  earth's  crust,  so  that  they  have 
acquired  altogether  different  characteristics  than  they  had  originally.  Such  a  change  in  rocks  is  called 
metamorphism. 

Does  solid  rock  appear  at  the  surface  anywhere  near  your  home? To 

which  of  these  four  classes  of  rocks  does  it  belong  ?     

At  the  next  period  bring  a  specimen  from  the  rock  outcrop. 


83 


• 


( 


Materials. 


Purpose. 


Steam  a 
cause  of 
porous 
lavas. 


XIX.  —  CLASSIFICATION  OF  IGNEOUS  ROCKS 

For  Each  Student.  —  A  specimen  of  pumice,  cellular  lava,  obsidian,  rhyolite,  granite,  trachyte, 
syenite,  gabbro,  basalt. 

For  General  Class  Use.  —  Small  pieces  of  rock,  unlabeled.  . 

To  become  familiar  with  the  general  types  of  igneous  rocks,  and  the  characteristics  by  which 
they  are  distinguished. 

When  water  is  boiling,  in  what  form  does  the  steam  rise  from  the  bottom  of  the  vessel  to 

the  surface  ? What  is  meant  when  we  say  that  the 

liquid  which  is  boiling  "froths  over"  ?   


If  this  "  froth  "  were  hardened  just  as  it  rises  over  the  rim  of  the  vessel,  what  would  be  the 
appearance  of  the  mass  formed  ?    


Classifica- 
tion by 
texture. 


If  molten  rock  were  being  "  frothed  over,"  or  blown  out  of  the  crater  of  a  volcano  by  the 
steam  and  gases  that  rise  from  it  (see  Fig.  203,  Text-book),  what  would  be  the  nature  of  the 

rock  that  is  formed  on  its  cooling? 

Which  of  your  specimens  shows  evidence 

of  having  had  such  a  history  ?    Which  one  shows 

evidence  of  less  violent  steam  action  ? 

If  the  molten  rock  flowed  over  the  volcano  rim  very  quietly  (like  molasses  candy  being 
poured  from  a  kettle),  and  then  cooled  quickly,  which  of  your  specimens  do  you  think  it 

would  most  resemble  ?   If  there  were  no  steam 

or  gas  in  the  lava,  which  specimen  would  result?  

Why  is  artificial  glass  similar  in  appearance  to  this  specimen?  


85 


Find   the   specimen   which  you   think   has   cooled  a  little  more  slowly  than  the  obsidian. 


What  specimens  give  evidence  of  the  following  condition  of  cooling :  First,  the  lava  cooled 
slowly  for  a  time,  at  a  rate  which  permitted  some  of  the  minerals  to  separate  out  and  form 
visible  crystals ;  then  it  cooled  rapidly  and  the  rest  of  the  mass  made  a  rock  of  fine  texture  ? 


What  minerals  have  separated  out  in  your  specimens  of  these  (porphyritic)  rocks  ?. 


Which  rocks  formed  in  the  places  indicated  in  Fig.  12  would  cool  rapidly  ?. 


Fig.  12.  —  To  illustrate  the  Origin  of  Igneous  Rocks. 


Would  this  give  rise  to  coarse  or  fine  grained  rocks? 

In  what  position  would  such  rocks  as  granite,  syenite,  and  gabbro  be  formed  ? . 


Classifica- 
tion by 
composi- 
tion. 


The  observations  you  have  made  above  give  a  basis  for  a  classification  of  igneous  rocks 
by  structure,  or  texture.  Pumice,  obsidian,  and  some  other  lavas  are  glasses.  Khyolite  and 
trachyte  are  porphyries.  Basalt  is  a  finely  crystalline  igneous  rock.  Granite,  syenite,  and 
gabbro  are  coarsely  crystalline  igneous  rocks. 

The  glasses  cannot  be  further  subdivided  (because  they  are  too  fine  grained)  ;  but  all  the 
other  rocks  are  also  grouped  according  to  their  composition. 

Refer  to  your  table  of  the  properties  of  minerals.     Which  minerals  are  light  in  color  ? 


86 


• 


Which  are  dark  ? 


In  which  of  these  two  groups  are  the  minerals  which  have  the  most 

metallic  elements  (iron,  magnesium,  calcium,  sodium,  and  potassium)?     

' Which  is  the  darker, 

orthoclase  or   plagioclase  feldspar  ?     Which  has  the  most  metals 

in  its  composition?     What  do  you  observe  as  to  the  relation  be- 
tween color  of  mineral  and  the  presence  of  metallic  elements  ?    1 


Arrange  all  your  specimens 

(except  the  glasses)  in  a  row,  putting  those  lightest  in  color  at  the  left-hand  side.     Write 

down  the  order  in  which  you  have  arranged  them.     


What  sort  of  a  rough  grouping  have 

you  now  made  of  the  rocks  ? 


Now  make  two  rows  of  your  specimens,  putting  the  porphyries  and  basalts  in  the  lower 
row,  but  still  keeping  the  specimens  in  the  same  order  as  to  color.     Write  down  the  order  of 

the  specimens  in  each  row. 


87 


Examine  your  granite  specimen  (which  should  be  first  in  the  upper  row).     What  minerals 

does  it  contain  (look  very  carefully)  ?     

Examine   the   syenite  (the   next   in   order).     What 

prominent  mineral  of  the  granite  does  it  lack?     Which  kind  of 

feldspar  has  it  ?     Examine  the  gabbro.     Which  kind  of  feldspar  has 

it? What  other  minerals  does  the  gabbro  contain ?     


A  rock  is  said  to  be  acid  when  it  is  made  up  mainly  of  the  light-colored  minerals,  which 
have  the  lesser  amounts  of  the  metal  elements.  The  rocks  in  which  the  minerals  have  metallic 
elements  are  said  to  be  basic.  Thus  quartz  is  the  most  acid,  and  pyrite  the  most  basic  of 
those  rock-forming  minerals  that  you  have  studied.     Which  of  the  rocks  in  your  collection 

are  acid  ?     


Which  basic  ? 


Whether  a  rock  is  acid  or  basic  gives  a  basis  for  a  second  method  of  classifying  igneous 
rocks ;  namely,  a  classification  according  to  composition.  In  the  following  table  write  in  the 
names  of  each  of  your  specimens,  keeping  in  mind  the  two  kinds  of  classification :  —  (1)  com- 
position; (2)  texture. 


88 


ACID  END 

BASIC  END 

>- 

Has  quartz  and  or- 
thoclase  feldspar 

Orthochase  feldspar 
but  no  quartz 

Has  plagioclase  feldspar 
and  other  basic  minerals 

Coarsely 
Crystalline 

Finely 
Crystalline 

Basalt 

Porphyries 

Glasses 

. 

By  means  of  this  table  identify  the  specimen  you  have  collected  from  the  home  locality  if  it  belongs 
among  the  Igneous  Rocks.  Identify  the  small  pieces  of  rock  given  you  by  the  teacher,  telling  (a)  the  minerals 
in  each  ;  (6)  whether  acid  or  basic  ;  (c)  its  texture  ;  (d)  its  name. 


t 


89 


Materials. 


Purpose. 


Sedimen- 
tary and 
organic 
rocks. 


XX.  — CLASSIFICATION   OF    SEDIMENTARY,   ORGANIC,   AND 
METAMORPHIC   ROCKS 

For  Each  Student.  —  Specimens  of  conglomerate,  sandstone,  shale,  limestone,  coal,  gneiss, 
schist,  quartzite,  slate,  marble. 

For  General  Class  Use.  —  Hydrochloric  acid  and  glass  stirring  rods.  Small  pieces  of  rock, 
unnamed. 

To  become  familiar  with  the  more  common  types  of  these  classes  of  rocks,  and  to  learn  how  to 
distinguish  between  them. 

Assume  a  stream  flowing  into  the  sea  and  carrying  along  in  its  current  small  pebbles, 
sand  grains,  and  clay  particles.  It  also  has  carbonate  of  lime  in  solution.  All  this  material 
the  stream  has  secured  along  its  course  by  the  breaking  up  of  some  kind  of  rock,  through  the 
action  of  the  agents  of  weathering  and  erosion. 

When  such  a  stream  empties  into  the  ocean,  will   its   current  continue  unchecked  in 

velocity?     ___.     Will  the  current  continue  at  all  for  any  great  distance 

from  the  shore?      What  then  will  become  of  the  rock  material  that  the 

current  is  carrying?     

Which  part  of  the  load  that  the  current  carries  will  be  deposited  first? 

Why?      ._ 


• 


Which  of  your  specimens  is  formed  of  such 

materials  ?     Which  kind  of  material  will  be 

deposited  a  little  farther  out  from  the  shore? '. 

What  kind  of  rock  does  this  make  ?     Which  of  your  specimens  might 

result  from  the  deposit  of  the  clay  particles  ?     

Which  of  your   specimens    might   have   resulted   from  the  deposit  of  the  lime   solution? 

How  might  the  sea  animals,  whose  traces 

are  shown  in  your  limestone,  aid  in  its  formation? . 


91 


Would  there  be  a  sharp  line  between  the  place  of  deposit  of  sandstone  and  conglomerate  ? 
Between  the  sandstone  and   the  shale?     Draw  a  diagram 


illustrating  deposit  of   sediment  in  the  sea  to  show  how  variation  in  texture  would  occur 
from  the  shore  outwards. 


Limestone  is  often  formed  from  the  remains  of  lime-secreting  animals.     Plant  remains  also 
form  organic  rocks.     Coal  is  such  an  organic  rock  formed  of  plant  remains  accumulated  in 

ancient  swamps.     Are  there  any  traces  of  plants  left  in  your  specimen? How 

could  you  test  whether  a  black  rock  was  coal  ?     1--, 

In  what  ways  do  sandstone  and  limestone  differ?      


Shale  and  limestone  (use  acid  test)  ? 


Shale  and  sandstone? 


92 


Sandstone  and  conglomerate? 


Identify   the  unlabeled    specimens. 


Metamor-  By  means  of  the  acid  test  find  which  of  your  metamorphic  specimens  was  changed  from 

phic  rocks. 

a  limestone.     Compare  it  with  limestone  and 

note  the  natur*e  of  the  change.     


Which  of  the  metamorphic  rocks  most  nearly  resembles  shale? 

How  does  it  differ  from  shale?     


Micaceous    minerals  are    abun- 
dantly present  in  slate,  and  you  may  be  able  to  see  them  in  your  specimen.     Why  would  the 

presence  of  such  minerals  cause  the  slate  to  split  so  regularly?     


• 


What  two  specimens  have 

been  so  metamorphosed  as  to  resemble  the  igneous  rocks  ?     


93 


Assuming  both  these  to  have  been  originally  clay  rocks,  which  has  apparently 

been  changed  most?     What  is  the  arrange- 
ment of  like  minerals  in  each?     

Why  is  it   easier  to   split   the  schist   than   the  gneiss  ? 


What  metamorphic  specimen  is  yet  unclassified?      From  what  is 

this  derived?     How  has   it  been  changed? 


Identify  the  unlabeled  specimens.     If  the  specimen  of  rock  from  your  home  locality  was  not  an  igneous 
rock,  identify  it  among  the  sedimentary,  organic,  or  metamorphic  rocks. 


94 


C 


# 


Materials. 


Purpose. 

Origin  of 
soil. 


XXI.— THE   SOIL 

For  Each  Student.  —  Specimen  of  rock  with  lichen  attached.  Several  rounded  stream  pebbles. 
Residual  soil  from  granite.  Residual  clay  from  limestone.  Field  soil  secured  from  beneath  sod. 
Small  fragment  of  limestone.     Hydrochloric  acid.     Test  tube.     Glass  plate. 

For  General  Class  Use.  —  Hand  specimens  of  minerals  and  rocks. 

To  study  the  origin  and  nature  of  soils  and  their  significance  to  man. 

From  your  study  of  minerals,  what  few  make  up  the  larger  part  of  the  rock  masses  of 

the  earth's  crust?     

Which  of  these  minerals  have  cleavage  planes?     

If  you  poured  water  over  minerals,  some  with  cleavage  planes  and  some 

without,  which  ones  would  absorb  the  water  most  readily  ?      

What  would  happen  if  the  water-soaked  minerals  were  to  freeze  ? 

, How   would   a 

rock  composed  of  cleavable  minerals  be  affected  if  first  soaked  by  rain,  and  then  exposed  to 
a  freezing  temperature?     


When  the  mercury  in  a  thermometer  tube  is  heated,  why  does  it  rise  ? 


Most  substances  have  this  property,  but  the  amount  of  expansion 

for  the  same  degree  of  heat  is  different  for  different  substances.     Thus  different  minerals 
expand  different  amounts  under  the  same  heat.     What  would  be  the  effect  on  the  rock  itself 

if  the  minerals  in  a  granite  expanded  at  different  rates?     


If  you  put  salt  in  water,  what  happens  ? 


If  you  put  acid  on  limestone,  what  happens  ?     1 

Other  acids  have  a  similar  effect.     Rain  water  obtains  carbon  dioxide  from  the  air  and  from 
plant  remains.    The  combination  of  the  water  and  carbon  dioxide  forms  carbonic  acid.    When 

95 


this  acid  soaks  down  to  the  soluble  limestone,  what  will  happen  ? 


Examine  the  rock  specimen  with  the  lichen  growing  on  it.     By  what  means  does  the 

plant  cling  to  the  rock  ?     

If  its  roots  grow  after  penetrating  a  tiny  crevice  in  the  rock,  what 
will  be  the  effect  of  their  growth  on  the  rock  ?     


State  clearly  the  general  effects  of  these  weathering  agents  on  all  minerals  and  rocks 
exposed  to  the  air.     

Have  all  minerals  cleavage  planes  ?     Are  all  minerals 

dissolved  by  acid?     Are  all  rocks  made  up  of  the  same  amounts,  or  of  the 

same  kinds  of  minerals  ?     What  bearing  have  these  differences  on  the  rate  at 

which  different  rocks  are  broken  down  ?      


Why  is  almost  all  the  earth's  surface  covered  with 

"dirt,"  sand,  and  clay,  while  bedrock  is  seen  only  occasionally  ?     


Examine  the  stream   pebbles.     Have  they  sharp   edges  and  corners?     

What    has    happened    to   the    pebbles    since   they    were    broken    off    from    the    bedrock  ? 


What  becomes  of  the  particles  which  are  ground  off? 

What  kind  of  deposits  do  they  form  in 

stream  beds  ?     


96 


Residual  Examine  the  residual  soil  from  granite  by  spreading  a  small  portion  on  your  glass  plate. 

soils. 

What  mineral  of  the  granite  has  remained  unaltered? What  mineral 

composes  the  greater  mass  in  a  granite  rock?  

What  material  seems  most  abundant  in  this  residual  soil  of  granite? 

What  has  happened  to  the  feldspar  of  the  granite? 

Put  a  small  fragment  of  limestone  in  a  test  tube  half  full  of  hydrochloric  acid.     What 

happens  ?     What  sort  of  material  remains  in 

the  test  tube  after  the  bubbling  ceases?      _. 

Examine  the  residual  clay  from  the  limestone. 

How  does  it  differ  in  composition  from  the  residual  material  of  granite?     


Why    is    there 

this  difference?     


The  original  limestone  rock  from  which  the  clay  has  been  derived  may 

be  gray,  brown,  or  black.     What  is  the  color  of  the  residual  clay  ?     

To  what  is  the  color  due?      

What  material  of  the  limestone  rock  remains  behind  as  residual  clay  ?     

Which  rock  would 

give  the  greater  amount  of  residual  material,  granite  or  limestone?     

Why?     


97 


il-             Examine  the  sample  of  field  soil.     How  does  it  differ  in  appearance  from  the  pure  resid- 
ual soils? 


Put  a  small  portion  of  the  soil  in  a  test  tube  f  full  of  water ;  shake,  and  then  allow  to  settle. 

What  kind  of  material  floats? What  is  the 

source  of  the  organic  matter?     : 

What  part  of  the  soil  remains  suspended  for  a  long  time? 

What  material  quickly  settles  to  the  bottom  ? 

How  does  the  field  soil  differ  in  composition 
from  the  pure  residual  soils?     


What  is  the  effect  of  the  presence  of  plant  roots  on  the  texture  of  the  field  soil? 

The  presence  of  organic  matter,  and  the 
greater  porosity  of  field  soils,  gives  them  fertility  and  enables  them  to  support  plant  life. 
The  subsoil,  in  which  plants  have  never  grown,  is  quite  infertile.  Why  then  would  it  be 
unwise    to    plow    up    soil    below    the    depth    to    which    plant    roots    usually    penetrate  ? 


Why  are  manures  placed  on  poor  soils  ? 


Where  do   growing  plants  secure  their  water  ? 


Will    plants    grow    well    in    a    very    compact    soil?     (See    suggested    home    experiment.) 
What  is  the  effect  of  plowing  the  soil  ?     ,. 


W 


98 


What  kinds  of  food  do  cattle  eat?     What 

kinds  of  food  does  man  eat?     Traced  back 

to  its  original  source,  what  is  the  real  basis  of  supply  of  food  for  man  ?     

State  clearly  the 

importance  of  soil  to  the  life  of  human  beings.     


Suggested  Secure  four  pans  about  three  inches  deep  and  eight  inches  long.     Into  two  of  these  put  clayey  field  soil, 

home  or  loosely,  and  in  each,  during  the  process  of  filling,  plant  20  grains  of  corn  at  a  depth  of  one  inch.     Keep  one 

general  of  these  pans  moderately  moist,  the  other  very  wet,  and  let  both  stand  in  a  warm  place. 

class  work.  Into  the  remaining  two  pans  put  the  same  kind  of  field  soil,  but  pack  it  very  firmly ;  and,  during  the 

process  of  filling,  plant  20  grains  of  corn  in  each  at  a  depth  of  one  inch.     Keep  one  of  these  moderately  moist, 
the  other  very  wet.     After  ten  days  observe  how  many  plants  are  growing  in  each  pan.    Under  which  treat- 


ment did  the  greatest  number  of  seeds  grow  ? 


The  least  ? 


What  was  the  effect  of  the  different  treat- 


ments of  the  soils  on  the  entrance  of  air  between  the  soil  grains  ? 


• 


What  is  the  effect  on  plant  life  of  pre- 


venting the  entrance  of  air  into  the  soil  ? 


Give  a  reason  why  fields  are  plowed. 


Why  a  field  should  be 


drained  of  its  surplus  water. 


99 


( 


A 


i 


SCALE. 
Fig.  13.  —  Contour  Interval. 


OF   THE 

UNIVERSITY 

OF 
s£4UF0RNVf 


MAKING   AND   INTERPRETATION   OF   TOPOGRAPHIC   MAPS 

XXII.  —  CONSTRUCTION   OF   AN  AREAL  MAP 

(With  tank  and  land  model,  see  page  viii) 

Materials.  For  Each  Student.  —  Ruler.    Pencil  (well  sharpened). 

For  General  Class  Use.  —  Land  model  and  tank.    Yardsticks. 

Purpose.  To  make  an  areal  map  of  a  miniature  land  form. 

Scale.  What  is  the  length  of  the  platform  on  which  the  land  model  rests? 

What  is  its  width?     What  is  the  length  of  the  accompanying  sheet 

of  paper  (Fig.  13) ?     Its  width?     If  your 

platform  were  five  feet  long  and  four  feet  wide,  and  your  paper  ten  inches  long  and  eight 
inches  wide,  what  would  be  the  greatest  amount  of  space  that  you  could  allow  for  every  foot  of 
the  platform,  if  you  were  asked  to  draw  an  outline  of  the  shape  of  the  platform  on  your  paper  ? 

.     What  explanation  would  you  need  to  put  on 

such  a  drawing  so  that  others  could  understand  what  the  size  of  the  original  was  ? 

What 

is  meant  by  the  scale  of  a  drawing  or  map  ?     


Why  would  it  be  more  convenient  to  adopt  a 

scale  one  half  that  of  the  largest  possible  scale  for  drawing  the  5x4  foot  platform  on  paper 

10  inches  by8  inches  in  size? 

What  does  the  phrase  1  inch  =  1  mile  (printed  on  many  maps) 

signify  ? 


From  your  measurements  of  your  own  platform  and  paper,  decide  what  will  be 

the  most  convenient  scale  for  you  to  adopt  for  the  map  you  are  to  make,  and  write  it  down 
opposite  the  word  "  scale  "  on  the  sheet  of  paper  (Fig.  13). 
Orientation  Turn  your  drawing  paper  so  that  the  arrow  printed  or*  the  sheet  points  to  the  north. 

Mark  an  N  above  it.     Mark  S  for  south,  and  E  and  W  at  the  proper  ends  of  the  other  lines. 

Which  side  of  the  model  will  you  draw  on  the  north  side  of  your  map? 


Holding  a  map  so  that  its  directions  correspond  with  the  actual 

directions  is  called  "  orienting  "  the  map.     Why  should  this  be  done,  whenever  possible,  when 

101 


using  a  map  of  any  kind  ? 


Areal 
mapping. 


Draw  an  outline  of  the  platform  according  to  the  scale  you  have  adopted.  Then  beginning 
on  the  side  assigned  by  the  teacher  (different  members  of  the  class  begin  on  different  sides), 
measure  with  the  yardstick  the  distance  from  the  edge  of  the  platform  to  different  points 
where  the  water  touches  the  land  model  (as  a-b,  Fig.  14).  Measure  only  to  the  prominent 
points,  such  as  the  ends  of  the  capes,  the  heads  of  the  bays,  etc.     Measure  also,  each  time,  the 


WATER 


MEASUREMENT  OUT 
-     TO  LAND  FORM 


MEASUREMENT  ALONG  PLATFORM 


=* 


16 


Fig.  14.  —  Diagram  to  show  Method  of  making  Measurements  for  Areal  Map. 

distance  from  a  corner  of  the  platform  along  the  edge  of  the  platform  to  the  point  from  which 
you  measure  out  to  the  land  model.  These  two  measurements  are  diagrammed  in  Fig.  14  as 
a-b  and  b-c. 

Then,  in  the  same  way,  locate  the  position  of  the  highest  points  of  mountains,  and  mark 
these  on  your  map  by  little  triangles  (  =  A ).  Next,  locate  the  course  of  the  main  streams  (as 
indicated  by  blue  yarn  on  the  model),  and  trace  a  line  on  the  map  to  show  each  of  these.  Lo- 
cate other  points  as  indicated  by  the  teacher. 

The  work  you  have  done  so  far  is  similar  to  the  work  that  topographers  do  when  making 
an  areal  map  of  a  similar  island  in  nature,  except  that  in  actual  land  mapping  you  would 
measure  with  instruments  from  point  to  point  on  the  island.  Also,  you  would  need  to  locate 
more  points.  Areal  mapping  means  locating  the  position  of  prominent  points,  streams,  roads, 
etc.,  in  a  given  area,  with  reference  to  each  other  and  to  the  cardinal  directions ;  and  also  de- 
termining their  latitude  and  longitude.     Could  you  tell  the  height  of  a  mountain  from  such  an 

areal  map?     Could  you  tell  whether  a  mountain  had  a  steep  slope  on  one 

side  or  a  gentle  slope  on  the  other?     Could  you  determine  the  form  of  a 

mountain  ridge  ?     What  two  features  shown  on  the  model  are  not  expressed 

on  the  map  as  you  have  made  it  up  to  this  point  ?     


102 


• 


Materials. 


Purpose. 

Base  level, 
or  datum 
plane. 


XXIII.  —  CONSTRUCTION  OF  A  CONTOUR  MAP 

For  Each  Student.  —  Ruler  and  brown  pencil,  well  sharpened. 

For  General  Class  Use.  —  The  model  used  in  the  previous  exercise  [and  if  plaster  model  is 
used,  a  number  of  boards  of  uniform  thickness  as  directed  on  page  ix  of  this  manual]. 

To  express  the  relief  features  of  a  miniature  land  form  on  a  map  by  means  of  contour  lines. 

What  line  on  the  areal  map  that  you  have  drawn  (Fig.  13)  shows  the  contact  of  water 

and  land?    

What  is  its  level,  with  reference  to  the  water  surface?      

What  kind  of  surface  has  a  body 

of  standing  water?     Why  are  all  elevations 

on  the   earth's   surface   expressed   by   their   height   in  feet  (or   meters)  above   sea  level  ? 


Why  is  the  mean  (or  average)  sea  level  often  referred  to  as  the  datum  plane,  or  base  level  ? 


Contour 
interval. 


The  water  in  the  tank  may  be  considered  as  a  miniature  sea. 

What  is  the  elevation  of  any  point  along  the  outline  of  the  map  you  have  drawn,  with 

reference  to  this  sea  level,  or  datum  plane  ?     

. Lower  the  model  and  its  platform  a  certain 

depth  into  the  water,  equally  on  all  sides.     How  much  did  you  lower  it  ?      

Has  the  water  level  changed?     Where  does  the  water  surface  come  into 

contact  with  the  land  now  ?     (Express  in  general  terms.)     


103 


Draw  (with  brown  pencil,  on  Fig. 

13)  the  new  outline  of  the  contact  of  the  land  surface  and  the  water  (making  measurements 
and  plotting,  as  done  previously  on  the  areal  map  you  have  made).     Does  this  new  outline 

come  outside  or  inside  the  original  outline  ?     

If  now  the  model  were  lifted  back  to  its  original  position  with  reference  to  the  water  level, 
and  a  path  were  traced  around  the  model  in  the  position  fixed  by  the  second  outline,  would 

this  path  go  uphill,  remain  always  at  the  same  level,  or  go  downhill  ? 


"What  then  is  the 


relation  of  the  second  outline  to  the  first  outline  ? 


Such  a  line,  drawn  on  a  map  through  all 

points  at  the  same  elevation  above  sea  level,  is  known  as  a  contour  line.     Why  should  the  dif- 
ference in  elevation  between  the  sea  level  and  the  contour  line  you  have  drawn  be  known  as  a 

contour  interval  ?      


Contour  Does  the  contour  line  that  you  have  drawn  extend  farthest  in  from  the  sea-level  line  at 

lines  and       points  where  the  slope  of  the  model  is  steep  or  gentle  ? 


slope. 


Succeeding 
contours. 


Lower  the  model  again,  the  same  distance  as  the  first  time.     Locate  and  plot  the  new 

contour  line.     What  is  the  contour  interval  you  have  adopted  ?     

Write  it  down  on  the  line  opposite  the  words  "Contour  Interval"  printed 

on  your  map  (Fig.  13).  Number  your  contour  lines  on  the  map  to  show  what  elevation 
above  the  original  sea  level  they  represent.  Lower  the  model  equal  distances  until  the 
highest  points  are  submerged,  and  draw  the  contour  lines  for  each  interval.     What  is  the  form 

of  the  cdntour  line  showing  the  highest  elevation  of  the  mountain  ?     

How  do  the  contour  lines  bend  when  they  enter  a  valley?      

W7hen  they  come  to  a  headland?     ___2 

"Where  are  they  farthest  apart,  on  steep  or  gentle  slopes?     

What  reason  can  you  give  for  using  a  brown  pencil 

in  drawing  the  contour  lines?     _ 


Use  of  a 
contour 
map. 


W7hat  does  a  contour  map  show  that  the  areal  map  did  not  ? 


Why    are    such    maps 


104 


• 


called   topographic    maps?     

Why  would   a  topographic   map   be  much  more   useful   than 

a  simple  areal  map  to  a  man  who  wished  to  make  a  road  between  two  points  ?     


How  could  one  find  out  from  a  topographic  map  how  many  feet  a  river  descended  from  its 
source  to  its  mouth?     


105 


€ 


€ 


• 


Materials. 
Purpose. 


XXIV.  — MAKING  A   CROSS   SECTION   OF   A   CONTOUR   MAP 

For  Each  Student.  —  Ruler.    Sharp  pencil.    Sheets  of  plain  paper. 

To  teach  the  making  of  cross  sections  from  contour  maps. 


• 


Fig.  15.  —  Contour  Map  of  Miniature  Land  Form  made  by  a  Student  in  Physical  Geography. 

Study  of  a  Figure  15  is  a  contour  map  of  a  miniature  land  form  made  by  a  student  in  physical 

simple  con-   geography, 
tour  map. 

What  is  the  scale  of  this  map?    

107 


What  is  the  contour  interval?     How  can  you  tell  which  slopes  on 

the  land  form  were  steep  and  which  were  gentle?     

: On  which  sides  of  the   miniature  land  form 

were  the  shores  steep?     

On  which  sides  did  it  have  gentle  slopes?     

, • What     was      the 

highest  elevation  on  the  land  form?     Why  was  this  figure  printed 

in  on  the  map?     T 

Which  contour  lines  are  heavier  than  others? 

What  aid  does  this  heavier  printing  of  some  contour  lines  give  when 

reading  the  map?     

By  what  other  means  are 

these  heavier  contours  distinguished  from  the  rest?     

On  the  northern  side  of  the  map,  the  two-inch  contour  line  bends  far  inland.     If  you  crossed 
the  miniature  land  form  in  an  east  and  west  direction,  would  you  find  the  land  inside  the 

bend  higher  or  lower  than  two  inches?     

What  would  be  the  case  if  the  contour  bent  outward  toward  the  sea? 

Find   and  note  an  illustration  of  a  contour  line  bending  outward. 

Meaning  of       Note  the  line  A-B  on  the  map,  Fig.  15.     What  are  the  elevations  of  the  two  highest  points 

cross 

section.  it  crosses  ? What  is  the  elevation  of  the  lowest 

point  it  crosses  between  these  high  points  ?     Make  a  drawing  (on  Fig. 

16)  to  show  how  your  path  would  go  uphill  and  downhill  if  you  were  to  cross  the  land  form 
along  the  line  A-B,  starting  at  A. 


-x 


A  B 

SEA-LEVEL  Fig.  16.  SEA-LEVEL 

The  drawing  you  have  made  is  a  crude  cross  section  of  the  land  form  along  the  line  A-B. 
If  a  cross  section  is  accurately  made  from  a  contour  map,  it  shows  clearly,  in  diagram  form, 

108 


Plotting 
| intersec- 
tions of 
contours. 


the  elevations,  depressions,  and  level  places  of  the  region  along  the  line  on  which  the  cross 
section  is  made. 

To  make  an  accurate  cross  section  along  the  line  A-B  proceed  as  follows :  Fold  a  sheet  of 
your  plain  paper  through  the  middle  so  that  you  have  a  smooth,  folded  edge  at  least  six  inches 
long.     Next  lay  this  paper  over  the  map  so  that  it  covers  the  southwest  corner  of  the  map,  and 


\  i,  L I  hi  y  i  I 


fc                     NOT                   < 

.-*            COMPLETED             ^ 

B 

FOLDED    SHEET 

OF    PAPER 

Fig.  17. 


Plotting 
the  inter- 
sections 
on  cross- 
section 
paper. 


so  that  the  folded  edge  rests  on  the  line  A-B,  leaving  this  line  visible.  At  A  and  B  draw  short 
(£")  vertical  lines  down  from  the  folded  edge  of  the  paper,  and  mark  A  and  B,  respectively,  at 
their  ends.  A  and  B  are  each  at  sea  level,  or  0  elevation.  With  sharp  pencil  mark  on  the 
folded  sheet  (with  similar  short  vertical  lines)  the  exact  point  of  intersection  of  each  contour 
line  with  the  folded  edge.  Begin  at  A  and  continue  to  B.  Below  each  vertical  line  indicate 
by  a  figure  the  elevation  of  the  contour  line  whose  intersection  it  marks.  When  this  operation 
is  partly  completed,  the  edge  of  your  folded  sheet  should  be  similar  to  Fig.  17. 

On  the  accompanying  cross-section  paper  (Fig.  18)  draw  a  pencil  line  along  one  of  the 
lower  horizontal  ruled  lines,  so  that  it  stands  out  distinctly  from  the  rest.  This  is  to  be  your 
0  line  or  sea-level,  or  base-level  line.  At  the  left-hand  end  of  the  zero  line,  draw  a  line  per- 
pendicular to  it,  and  13  small  squares  high.     Number  the  horizontal  lines  which  this  perpen- 


INCHES 

11 
10 
9 
8 
7 
f 
6 
4 
3 
2 
1 

i 

|            1 
1"       2" 
\ 

JJ'e"!     H"         i."                  J"                                                                       6"i„    ^     NOT  COMPLETED 

3" 

1 

Fig.  19.  —  To  illustrate  Method  of  making  Cross  Section  from  Contour  Map. 

109 


dicular  crosses,  from  1"  to  13";  the  1"  line  being  the  one  next  above  the  zero  or  sea-level  line. 
Mark  this  end  of  the  drawing  A. 

Now  lay  the  folded  edge  of  the  sheet,  on  which  you  have  marked  the  intersections  of  the 
contours  along  the  sea-level  line,  so  that  the  point  A  on  the  folded  edge  coincides  with  the 
point  A  on  the  horizontal  line  of  the  cross-section  paper.  Next  make  a  dot  with  your  pencil 
on  the  1"  horizontal  line  of  the  cross-section  paper,  at  a  point  exactly  above  the  place  where 
you  have  marked  the  intersection  of  the  1"  contour  line  on  the  folded  edge.  For. the  2"  con- 
tour intersection  put  a  dot  on  the  2"  horizontal  line;  and  so  on  until  you  have  put  dots  on  the 
proper  horizontal  lines  for  all  the  contour  intersections,  and  have  reached  sea  level  again  at  B. 
Next  connect  the  dots  by  means  of  a  smooth  curved  line,  avoiding  sharp  angles.  When 
partly  drawn,  your  cross  section  should  be  similar  to  Fig.  19. 
Horizontal  The  scale  of  the  map  was  1  inch  =  l  foot.      Therefore  the  horizontal  scale  of  your  cross 

and  vertical  section  is  the  same,  and  you  should  print  or  write  this  below  your  cross  section,  thus :    Hori- 
scale. 

zontal  Scale  1  inch  =  1  foot.     What  is  the  vertical  scale  of  your  cross  section?    

Above  the  cross  section,  write  "Cross  Section,  along  the  line  A-B 

on  Map,  Fig.  15."     Always  mark  the  vertical  and  horizontal  scale,  and  the  line  along  which 
it  is  taken,  on  every  cross  section  you  make. 


110 


1 1 1 _ 1         ,         I i 1 —J __- . ( 1 1 1 1 1 1 . ' 1 ' 1 — 

. . 1 , , ___ ___  _ . 

i l—J 1 .  i  1 , 1 1 1         I 1 — 1 ' 

— — — ■ — I.     i  ■      — — — | — i     i     — —  — i — i     i     i i j , i L_J , , __ i 

— __ , , __ . 

»' — I — ' — • — ' — '     '     ' 1 — • 1 — < — i 1 • — ' 1 1 — 1 — . 1 — i — 1 — I — i — i , i - , i i ; 
:____:                            zzEffi 

, 


• 


Streams 


RELIEF 


Contours 


Figures 

(showing  heights  above  (showing  height    above 

mean  sea  level  instru-  sea<   horizontal  form, 

mentally  determined)  and  steevness  of  slope 


Depression 
contours 


of  the  surface) 


Cliffs 


Falls  and 
rapids 


Intermittent 
streams 


Mine  dumps 

WATER 

A 


Canals  and 
ditches 


Levees 


Sand  and 
sand  dunes 


Aqueduct 


Aqueduct 
tunnel 


I 


Lake  or 
pond 


Intermittent 
lake 


Glacier 


Spring 


Salt  marsh         Fresh  marsh 

CULTURE 

A 


Submerged 
marsh 


= — ii  it  i  fin 


I  I  I  I  I  I  I  I  I 


II  I  I  I  I  *=*= 


Tidal  flat 


City  or 
village 


Roads  and  Private  or 

buildings  secondary  road 


Trail 


Railroads 


Electric  railroad 
in  roadway 


i 


n 


,x* 


v~— ««> 


Ford 


Dam 


Locks 


U.S.township  and        State  line 
section  lines 


County  line        Civil  township 
line 


U'1I< 


Boundary 
monument 


Bench  mark 


Church  or 
schoolhouse 


Coke  ovens 


Oil  wells 


Mine  or 
quarry 


Prospect 


Tunnel 


Wharves 


Breakwater 
and  jetties 


Drawbridges 


Bridges 


Ferry 


Reservation 
line 


Land-grant         City.village,or  Park  or 

line  borough  line         cemetery  line 


Triungulation 
station 


U.S. mineral 
monument 


$,  LS 


%LH 


Shaft 


Mine  tunnel  Mine  tunnel  Light-ship 

(showing  direction)  (direction  unknown) 


Lighthouse 


Life-saving 
station 


Fig.  20.  —  Conventional  Signs  used  on  Atlas  Sheets  of  the  United  States  Geological  Survey's  Topographic  Maps. 


1 


XXV.— MAKING  A  CROSS  SECTION  AND  A  STREAM  PROFILE 
FROM  A  UNITED  STATES  TOPOGRAPHIC  MAP 

Materials.  For  Each  Student. — Ruler.    Pencil.  Several  sheets  of  plain  paper.    Montross  sheet.   Maryland- 

Virginia. 

Purpose.  To  teach  the  understanding  of  the  conventional  signs  used  on  a  topographic  map,  and  the 

making  of  cross  sections  and  profiles  from  such  maps. 

Conven-  Figure  20  illustrates  the  conventional  signs  used  on  the  United  States  Geological  Survey 

tions  of  a 

topographic  topographic  maps.     What  color  is  used  for  contour  lines?  > What  is 

map. 

meant  by  Relief? 

What  color  is  used  for  road,  county,  and  state  lines,  and  for  buildings  and  cities  ? 

Why  should  these  features  be  called  cultural  features?  


What  color  is  used  to  indicate  water  ? 


Cross  sec-  Make  a  cross  section   (on  accompanying  sheet  of  cross-section  paper)    of  part  of  the 

tionofa  Montross  sheet  along  a  line  between  Stony  Hill  and  Montross,  proceeding  as  you  did  in 
topographic  making  the  cross  section  of  the  simple  contour  map  in  the  preceding  exercise.  A  very  sharp 
maP-  pencil  and  even  greater  care  will  be  necessary.      In  making  the  cross  section  note  carefully 

whether  you  are  crossing  a  valley  or  a  divide  between  valleys. 

Exaggera-  What  is  the  horizontal  scale  of  the  map  ? 

tion  of 

relief  in  a      What  is  the  contour  interval? '_ What  is  the  vertical  scale  of  your 

cross 

sec  ion.         cross  section  ? If  the  horizontal  scale  of  your 

cross  section  is  one  inch  =  one  mile,  and  your  vertical  scale  is  \  inch  =  20  feet,  how  much  is 

your  vertical  scale  exaggerated? (5280  feet  =  l 

mile,  therefore  5280  feet  =  linch  horizontal  scale.  8  x20  =  160  feet,  therefore  160  feet  =  1  inch 
vertical  scale.  Therefore  in  the  cross  section  160  feet  vertical  scale  equals  5280  feet  in 
the  horizontal  scale.) 

Why  would  it  have  been  much  better  to  use  a  vertical  scale  \  inch  =  80  feet  ?  .... 


J 


Plot  the  same  cross  section  on  this  scale.     What  is  the  exaggeration  of  the  vertical  scale  in 

111 


this  case  ? Always  endeavor  to  avoid  too  great 

exaggerations  of  the  vertical  scale  in  making  cross  sections  and  profiles. 
Profile  of  On  the  map  locate  the  main  stream,  which  occupies  the  valley  between  Chilton  and 

a  stream        Stratford,  and  is  crossed  by  the  road  which  connects  these  villages.     Trace  this  stream  from 
va  ey'  its  source  to  the  point  where  it  flows  into  the  lake. 

How  many  contour  lines  does  the  main  stream  cross  in  that  distance? 

How  many  feet,  therefore,  does  it   descend? In  about  how  many 

miles  ?   

Make  a  profile  of  this  valley  between  its  source  and  its  entrance  into  the  lake.  The  method 
is  the  same  as  for  making  a  cross  section,  except  as  follows :  Start  at  the  left-hand  end  of 
the  folded  paper  in  marking  the  intersections  of  the  contours.  As  often  as  the  stream  bends 
appreciably,  swing  your  folded  edge  of  paper  so  that  it  is  continually  parallel  to  the  stream's 
course.  Be  careful  to  keep  the  pivot  point  on  the  map  and  on  the  folded  edge  of  the  paper 
identical  when  swinging  the  paper  to  a  new  direction.  Plot  the  results  on  the  cross-section 
paper,  using  this  time  a  vertical  scale  of  \"  =  40  feet. 

Where  is  the  stream's  profile  steepest?   

In  what  portion  of  its  course  is  it  most  gentle? 

What  is  its  average  descent  per  mile  near  its  source  ? 

In  the  middle  of  its  course? 

What  information  regarding  a  region  can  be  gained  at  a  glance  from  a  cross  section  ? 


Of  what  practical  use  would  a  profile  of  two  possible  roads,  that  he  might  follow,  be  to  a 
farmer  intending  to  haul  grain  to  town  ? 


112 


9  PHYSIOGRAPHY   OF   THE   LANDS 

XXVI.  —  PROCESSES   OF   EROSION   AND   DEPOSITION 

Materials.  For  General  Class  Use.  —  Tank  and  land  model.    Spray,  nozzle,  and  hose.     (The  nozzle  should  be 

of  the  kind  used  in  spraying  trees  for  insects.)    Water  under  pressure. 

Purpose.  To  study  some  of  the  erosional  and  depositional  processes  of  nature  by  actual  observation  of 

their  progress  in  miniature. 

The  land  This  land  form  is  supposed  to  have  been  newly  uplifted  from  beneath  the  sea,  and  no 

form.  rain  has  as  yet  fallen  upon  it.     It  is  composed  of  alternate  layers  of  sediment,  formed  of 

different  kinds  of  material. 

With  reference  to  the  compass  directions,  describe  the  topography   of  the  land  form. 

Where  is  it  hilly?     


Where  has  it  plains?     

Are  there  any  mountain  ranges  ? 

Are  there  plateaus ?     Any  isolated  peaks?     

what  material  is  the  surface  layer  composed?     


Of 


Character-  Turn  the  spray  upon  the  land  surface.     Have  it  of  sufficient  volume  to  develop  streams, 

istics  of  a  bufc  avoid  having  the  drops  of  water  too  coarse.     This  spraying  is  to  simulate,  as  nearly  as 

young  land  poggikig  the  rainfall  of  nature, 

surface.  r 

What  determines  the  courses  of  the  streams  as  they  flow  at  first?      , 

. Why      are      such 

streams  called  consequent  streams?     

Do  any  lakes  form  ?     What   is   the 

origin  of  their  basins?     

Are  the  divide  areas  between  the  stream  courses  flat  or  ridgelike  ? 

What  age  condition  of  a  land  surface  does  the  presence  of  consequent 

streams,  lakes,  and  flat-topped  divides  indicate?     


Examine  the  stream  currents  carefully.     Are  they  carrying  sediment  ? 

113 


Transpor-      If  so,  where  do  they  get  it? 

tation  and 

erosion 

processes.       


Are  they  carrying  sand  particles? How  are 

the  sand  particles  moved  along?     

How  much  larger  stream  do  you  think  would  be  required 

to  move  a  pebble  as  big  as  your  fist?     How 

are  clay  particles  carried  along?     , 

Can  you  tell  whether  the  streams  are  carrying  any  material 

in  solution?    

As  the  currents  transport  the  sand  and  clay  particles,  what  is  the  effect  on  the  stream 

valleys?       

Where  are  they  deepened  most?     

What     is     meant    by    headwater    erosion? 


Do  the  main  streams  follow  straight  courses  ?     What  causes  them  to  meander  ? 


What  is  the  effect  of  this  meandering  on  the  width  of  their  valleys  ?     .. 
What  is  meant  by  lateral  cutting  of  a  stream? 


By  undercutting  f    .. 


114 


What   is  the  shape  of  the  cross  section  of  the  stream  valleys  as  they  are  first  cut  ? 
How  is  this  "gorge-form  "  cross  section  changed  by  the  lateral  cutting?     


Do  tributary  streams  first  deepen  their  valleys  near  their  sources  or  at  their  junction 

with  the  main  valleys?     How  do  you  explain 

this?     1 


What  effect  has  the  development  of  tributary  valleys  on  the  flat-topped  divides? 


Waterfalls.  Have  any  waterfalls  developed  in  the  stream  valleys?      What  is  their 

cause?     


Why  does  a  deep  pool  form  beneath  them  ? 


Why  do  the  waterfalls  not  remain  stationary  in  position  ? 


In  which  direction  do  their  crests  move  ? 


Deposi-  Are  the  sand  particles,  which  the  currents  are  rolling  along,  carried  uninterruptedly  to  the 

tional 

processes.      still  water  at  the  mouths  of  the  main  streams  ?     Where  do  they  lodge  ? 


What  do  they  form?     Are  river  bars  permanent? 

115 


What  is  the  effect  of  the  formation  of  a  bar  on  the  course  of  a  stream?    

What  large  river  do 

you  know   of    which  has   many    sandbars?    

Why  are  these  dangerous  to  navigation  ?     


Which  can  carry  the  most  sediment,  a  slow  current  or  a  fast  one?     

Where  are  currents  fastest,  on  steep  or  on  gentle  slopes  ?     

If  a  stream  has  much  sediment  in  the  upper,  steep  part   of  its 

course,   what    becomes  '  of    this   sediment   when   the   stream   flows   over   a  gentler   slope  ? 

Examine  the  streams  on  the  land  form  to  find 

such  a  condition.     What  kind  of  a  topographic  feature  results?     

Describe  and  make  a  small  sketch  of  an  alluvial  fan.     


Watch  the  stream  course  as  it  flows  over  the  alluvial  fan ;  why  does  it  shift  its  position  ? 


Does  the  building  up  of  the  alluvial  fan  make  the  slope  of  the  stream  steeper  or  more  gentle 
at  this  point?     What  is  the  grade  of  a  stream  ? 


116 


What  becomes  of  the  sediment  that  the  stream  carries  when  it  enters  the  still  water  ? 

Where    are     the    sand    particles    deposited? 

Where   are   the   clay   particles   deposited? 

Which  kind  of  deposit,  sand  or  clay,  covers 

the  larger  area  of  the  bottom  of  the  still-water  basin?     

What  topographic  form  do  the  sand  particles  build  up  as  they  are  deposited  in  the  still 

water?     Is   the   slope  of  the   top  of   the   delta   steep   or   gentle? 

How  does  the  delta  compare  and  contrast  with  the  alluvial  fan  in 

outline  and  slopes?   . 


117 


• 


XX VII.  —  INTRODUCTION   TO   THE   STUDY   OF   LAND   FORMS 


Purpose. 


Types  of 
land  forms. 


Factors  in 
the  devel- 
opment of 
land  forms. 


Topo- 
graphic 
provinces 
of  the 
United 
States. 


To  teach  the  simple  origin  of  land  forms,  and  the  factors  which  give  them  complexity. 

Note:  —  This  section  should  be  carefully  studied  before  going  on  with  the  study  of  the  land  in  its  topo- 
graphic and  cultural  relations. 

Most  land  forms  are  the  result  of  the  processes  of  denudation  operating  on  the  rocks 
of  the  earth's  crust. 

The  nature  and  configuration  of  these  forms  are  dependent  primarily  and  fundamentally 
on  the  position  and  structure  of  the  rocks.  There  are  two  fundamental  types  occupying  large 
areas : — 

1.  The  Plain-plateau  Type:  The  rocks  are  in  horizontal  or  nearly  horizontal  beds. 

2.  The  True-mountain  Type :  The  rocks  are  folded,  faulted,  and  tilted,  or  are  massive 
crystalline  rocks. 

Most  lesser  land  forms  are  resultant  upon  variations  in  the  conditions  and  nature  of  the 
denudation  of  these  simple,  original  forms. 

The  following  factors  condition  the  variation  :  — 

(a)  The  nature  of  the  rock,  whether  consolidated,  or  unconsolidated,  or  partly  consolidated. 

(6)  The  length  of  time  that  the  region  has  been  exposed  to  denudation. 

(c)  The  elevation  of  the  region  above  sea  level,  and  its  distance  from  the  sea. 

(d)  The  climate,  —  whether  humid  or  arid. 

(e)  Accidents  which  have  interfered  with  the  normal  development  of  the  region.  Glaci- 
ation  and  volcanic  disturbances,  for  example,  may  be  considered  as  such  accidents. 

With  a  knowledge  of  the  primary  type,  whether  Plain-plateau  or  True-mountain,  and  a 
consideration  of  the  degree  to  which  the  five  factors  enumerated  above  have  been  operative, 
we  can  interpret  most  land  forms.  Or,  by  a  consideration  of  the  land  forms,  we  can  appreciate 
the  factors  which  determine  their  present  condition. 

That  part  of  North  America  which  comprises  the  United  States  is  capable  of  being  divided 
into  a  comparatively  small  number  of  areas,  each  of  which  constitutes  a  physiographic  unit,  or 
province.  Moreover,  these  units  bear  a  most  interesting  physiographic  relation  to  each  other ; 
and,  taken  collectively,  they  illustrate  practically  the  whole  science  of  the  physical  geography 
of  the  land.  Again,  in  each  of  these  physiographic  provinces  the  United  States  Geological 
Survey  has  made  very  fine  contour  maps,  and  from  these  may  be  chosen  one  or  more  which 
are  typical  of  the  province. 

The  United  States,  therefore,  offers  to  the  American  student  an  excellent  opportunity  to 
become  acquainted  with  the  science  of  physical  geography  of  the  land  in  some  of  its  most  in- 
teresting phases,  and  to  gain  a  knowledge  of  the  physiographic  provinces,  and  the  influence 
their  topography  and  structure  have  had  on  the  development  of  the  land,  its  present  industries, 
and  its  future  possibilities. 

The  following  sections  constitute  such  a  study  of  the  regions  of  the  United  States.  The 
studies  go  from  the  simple  to  the  complex,  and,  when  they  are  completed,  the  student  should 
have  a  comprehensive  knowledge  of  the  location  of  the  broader  physiographic  divisions  of  the 
country  ;  and  an  understanding  of  the  topographic,  climatic,  and  cultural  relations  of  each. 


119 


3 


Bill! 
22 


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III 

a, 

S 

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J  ft, 

5 

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°: 

11 
S-s 

4 

e  1 

XXVI II.—  GLACIAL-LAKE   PLAINS 


Materials. 


Purpose. 


Introduc- 
tory. 


Extent  of 
the  Glacial- 
Lake  areas. 


For  Each  Student.  —  United  States  Geological  Survey  Map  of  the  United  States  (size  18x28 
inches)  with  contours.     Fargo  sheet,  North  Dakota-Minnesota.     Colored  pencils. 

To  study  a  very  young  plain  and  the  influence  it  exerts  on  human  habitation  and  industrial 
development. 

When  the  Continental  Glacier  of  the  Glacial  Period  was  receding,  after  the  last  (or  Wis- 
consin) advance  of  the  ice  (Text-book,  Chapter  VIII),  and  had  melted  back  to  points  near  the 
northern  boundary  line  of  the  United  States,  there  were  times  when  the  ice  front  remained 
stationary  for  a  considerable  interval.  During  this  long  period  of  recession  the  ice  mass 
dammed  up  the  north-flowing  rivers  (for  example,  the  Red  River  of  the  North),  and  their 
waters  spread  out  and  formed  huge  lakes.  (See  Text-book,  pp.  78  and  149.)  Into  these  lakes 
much  sediment  was  poured  by  the  streams  from  the  glacier  and  from  the  land,  and  this  sedi- 
ment was  deposited  on  the  lake  bottom.  Finally,  after  the  glacier  had  melted  away  com- 
pletely, the  lake  waters  drained  off  and  the  bottoms  of  the  lakes  became  dry  land. 

Figure  21  is  a  diagram  map  of  the  United  States  on  which  have  been  outlined  the 
different  physiographic  regions  studied  in  this  and  succeeding  sections.  The  areas  which  are 
marked  "  G.  L.  P."  on  the  map  were  formerly  bottoms  of  glacial  lakes.  Plot  the  outlines  of 
these  Glacial-Lake  Plains  on  your  contour  map  of  the  United  States.  Latitude  and  longitude, 
the  position  of  state  boundary  lines,  and  the  location  of  cities  offer  the  best  aids  in  locating 
the  outline.     Extend  the  Glacial-Lake  Agassiz  outlines  into  Canada. 

Examine  the  areas  as  you  have  outlined  them  on  your  map  of  the  United  States.  About 
what  proportion   of  the  area  of   the   United   States   was  once   covered  by   glacial   lakes  ? 

What  two  places  along  the  outlines  seem  to 


have  been  outlets  to  these  lakes? 


What  is  the  highest  contour  bordering  each  of  these  out- 


flow channels  ? 


Why  was  there  an  island  in  the  Glacial-Lake  Agassiz  ? 


With  green  pencil,  color  in  lightly 

(on  your  contour  map  of  the  United  States)  the  regions  of  the  Glacial-Lake  Plains.  Fill  in 
(with  green  also)  a  square  for  a  legend,  as  indicated  on  the  outline  map.     Label  this  square 

Study  of  a     «  Glacial-Lake  Plains." 

of  the  Gla-  Examine  the  Fargo  (N.  D.)  sheet.     What  is  the  most  northern  degree  of  latitude  shown  ? 

cial-Lake 

Plains.  The   most   southern?     Between  what 

121 


degrees  of  longitude  is  the  area  included?     

Locate  this  area  on  your  United  States  map  and  outline  it  with  ink.     Letter  or  write  in  the 
name  of  the  sheet  beside  the  rectangle  you  have  drawn.     How  much  larger  is  the  horizontal 

scale  of  the  topographic  map  than  that  of  the  United  States  map  ?     


What  is  the  contour  interval  of  the  topographic  sheet  ? 


A  typical  Make  a  cross  section  between  the  S  of  Sabin  and  the  H  of  Horace,  using  the  same  hori- 

cross  sec-      zontal  scale  as  that  of  the  map,  and  allowing  one  vertical  division  of  the  cross-section  paper 

tion.  £or  everv  20  feet  of  elevation.     On  each  cross  section  you  make  always  mark  the  name  of  the 

sheet,  the  points  between  which  it  is  taken,  the  horizontal  scale,  and  the  vertical  scale  adopted. 

What,  in  general,  is  the  nature  of  this  land  surface,  as  shown  by  the  distance  apart  of  the 

contour  lines  and  the  cross  section  you  have  made?     

What    is   the   shape   of  •  the    stream 

valleys  as  shown  by  your  cross  section  ?     

How  deep  are  they  ?     

How  wide?      

Are  this 

shape    and    size    characteristic    of   an   old   or    young    valley?     

What    is   the   nature   of    the   divides    between    the   stream 

valleys  ?     Why  would  rain  water  run  off 

very  slowly  from  this   region?     In  which 

direction  do  the  main  streams  flow? ;._  What 

is   the    difference    in    elevation    between    the   highest    and    lowest    points    on   the    map  ? 

Where   is  the  highest  point  ?     

The  lowest  point  ?     

What  are  the  directions  of  the  wagon  roads  in  this  region  ?     

What  is  their  pattern,  or 

arrangement  ?     Why  is  it  possible  for  the 

railroads  to  have  such  straight  courses?     

What  kind  of  deposits  are  laid  down  in  still  water,  fine  or  coarse  grained?     

What  two  reasons  can  you  give  why  this  should  be  a  fine  agricultural  region? 

122 


Why  are  many  farmers  now  crossing  into  Canada  to  the  region  north  of  this  part   of  the 
United   States?      


Count  the  number  of  houses  in  ten  adjoining  squares.     Allowing 

five  people  to  each  house,  what  is  the  average  population  per  square  mile  in  this  section  ? 

What   is   the  position   of    the   houses   with 

respect  to  the  roads  ?     ' 

Write  a  short  paragraph,  below,  explaining  why  the  deposit  of  sediment  over  a  lake 
bottom  would,  on  the  disappearance  of  the  lake  waters,  give  a  region  of  this  nature,  and  tell 
why  such  a  region  encourages  agricultural  industry. 


123 


XXIX.— THE  MISSISSIPPI  FLOOD  PLAIN  AND  DELTA 

Materials.  For  Each  Student.— Geological  survey  map  of  the  United  States,  used  in  preceding  exercise. 

Donaldsonville  (La.)  sheet.    Colored  pencils. 

For  General  Class  Use.  —  Chart  No.  14.    Mississippi  River  Commission.    The  Fargo  (N.  D.)  sheet. 

Purpose.  To  study  a  very  young  plain  in  process  of  formation  by  liver  deposit;  and  the  conditions  affect- 

ing human  occupation  of  this  plain. 


Introduc- 
tory. 


Extent  of 
the  Missis- 
sippi Flood- 
plain  and 
Delta  area. 


The  Mississippi  River,  in  its  lower  course,  carries  enormous  amounts  of  sediment  in  its 
waters.  In  places  it  deposits  some  of  this  sediment,  in  others  it  secures  more.  At  its  mouth 
it  deposits  all  its  load.  The  flood  plain  and  delta  of  the  Mississippi  are  built  up  of  such  sedi- 
ment deposits,  and  the  river  is  continually  modifying  the  flood  plain,  and  extending  the  delta. 
(See  Text-book,  pp.  61-66,  325-328.) 

On  your  contour  map  of  the  United  States  plot  the  outline  of  the  area  marked  M.  Fl.  P. 
and  D.  on  Fig.  21.  About  what  proportion  of  the  area  of  the  United  States  does  the  Missis- 
sippi Flood-plain  and  Delta  region  constitute?     What  is  the  approximate 

length  of  this  area  in  miles?     1 What  is  its 

average  width?     What  is  the  pattern  of  the 

smaller  streams  on  the  flood  plain  and  delta?    


Study  of 
Mississippi 
liver 
Jhart 
"No.  14. 


Are  they  many  or  few  as  compared  to  adjoining  regions  ? 


At  the  mouth  of  the  Ohio  River  the  altitude  of  the  Mississippi  River  is  294  feet  above  the  sea. 
The  distance  from  the  mouth  of  the  Ohio  to  the  mouth  (head  of  passes)  of  the  Mississippi  is 
1060  miles.     What  is  the  average  descent  (in  feet  per  mile)  of  the  Mississippi  between  the 

mouth  of  the  Ohio  and  its  mouth  at  the  Gulf  of  Mexico  ? 


With  blue  pencil,  color  in  lightly  on  your  contour  map  of  the  United  States  the  area  of 
the  Mississippi  Flood-plain  and  Delta  region.  Fill  in  (with  blue  pencil  also)  a  legend  square, 
as  indicated  on  the  outline  map  (Fig.  21). 

What  is  the  scale  of  this  chart?     

What  is  the  nature  of  the  river's  course  as  shown  on  this  chart?     

125 


How  long  are  the  river  bends?     

. On  which  side  of  the  bends  is  the  river  depositing  material? 

Do  these  bars  have  a  constant  shape  and  position  ?     (See  red  lines  and  legend  explaining  them.) 


Which  is  the  shortest  course,  around  the  bends  or  across  the  necks  of  land  between  them  ? 

Why  does  the  river  often  change  its  course,  especially  during  a 

flood  when  part  of  the  waters  can  flow  over  such  necks  of  land?     


What  does  the  abandoned  portion  of   the   river  become  after  a  new  course  is  established? 

Give  an  example  of  such  a  change  as  shown 

on  the  chart. 


Why  must  the  river  be  often  resurveyed' 


Study  of  a  The  Donaldsonville  (La.)  sheet  shows,  in  detail,  typical  conditions  of  this  region.     Locate 

typical  Mis-  and  plot  the  area  of  this  sheet  on  your  United  States  map,  outlining  it  with  ink.     Letter  or 

sissippi         write  in  the  name  of  the  sheet. 

Flood-plain 

and  Delta 

area  WThat  is  the  contour  interval  on  this  sheet ?     Why  was  not  a 

larger  interval  used?     

Make  a  cross  section  between  Bayou  Verrette  and  the  nearest  point  of  the  swamp  on  the 
opposite  (east)  side  of  the  river.  Allow  one  vertical  division  of  your  cross-section  paper  for 
every  ten  feet  of  elevation.  On  the  cross  section,  indicate  the  line  along  which  it  is  made,  and 
also  the  horizontal  and  vertical  scale. 

126 


As  shown  by  your  cross  section,  where  are  the  highest  points  in  the  flood  plain  ? 
How  do  you  explain  this  condition?     (Natural  levee,  Text-book,  p.  62.) 


In  what  direction  do  the  small  streams  near  the  Mississippi  flow? 

Why  can  not  the  large 

swamps  be  drained?     


Why  does  the  Mississippi  so  readily  change  its  course  in  flood  times  ? 


What  is  the  stage  of  the  development  of  drainage  conditions  here,  as  compared  to  those  in 
the  Glacial-Lake  Plains  regions?     


Is  this,  then,  a  younger  or  older  region  in  development  than  the  Glacial-Lake  Plains  areas  ? 


Human  Describe  the  position  and  course  of  the  main  roads  of  this  area, 

occupation. 


How  do  you  account  for  their  arrangement  ? 


127 


What  is  the  direction  of  the  secondary  roads  ? 


.Where  do  they  end  ? 


What  is  the  average  width  of  the  habitable  area  of  the  inner  flood  plain,  as  shown  on  this 

sheet?     

Where  are  the  majority  of  the  houses  located?     

About  how  many  houses  are  there  along  a 

mile  of  river  bank? What  population  per 

square  mile  does  this  indicate?     

Does  such  a  population  indicate  that  the  flood  plain   is   rich   or   poor   agricultural   land  ? 

Why  is  a  region  with  such  large  areas  of  swamp  land  not  healthful? 


Write  a  short  paragraph  summarizing  the  conditions  along  the  Mississippi  River  in  its 
lower  course. 


128 


XXX.— THE   COASTAL   PLAIN 

Materials.  For  Each  Student.  —  The  contour  map  of  the  United  States.    Winterville  (N.C.)  sheet.    Colored 

pencils. 

For  General  Class  Use. — Fargo  (N.D.)  sheet.    Donaldsonville  (La.)  sheet. 

Purpose.  To  study  a  young  plain  recently  uplifted  above  sea  level,  and  to  compare  the  conditions  on  it 

with  that  of  other  young  plains  previously  studied. 


Introduc- 
tory. 


Extent  of 
the  Coastal 
Plain. 


The  region  of  the  United  States  bordering  the  eastern  and  southern  coast,  from  New 
York  City  southward  to  Mexico,  except  where  broken  by  the  Mississippi  flood  plain  and 
delta,  is  a  Coastal  Plain.  That  is,  it  consists  of  layers  of  sediment  deposited  on  the  ocean 
floor  and  then,  by  a  change  in  the  level  of  the  land,  lifted  out  of  the  water.  (Text-book,  pp. 
72-75,  305-306.) 

On  your  contour  map  of  the  United  States  plot  the  outlines  of  the  areas  marked  Coastal 
Plain  in  Fig.  21.     Estimate  what  proportion  of  the  area  of  the  United  States  the  Coastal  Plain 

region  constitutes.     Of  what  states  does  it 

form  the  larger  part?     


Broad  Southern  Florida  is  different  from  the  rest  of  the  Coastal  Plain  in  that  it  is  underlain  by 

relations.       limestone.     How  may  this  fact  account  for  the  many  lakes  mapped  on  its  surface  ?     (Text- 


book, p.  60.) 


What  other  region  having  many  lakes  have  you  studied?  

What  does  the  presence  of  lakes  and  swamps  indicate  as  to  drainage  conditions  ? 


Along  the  inland  margin  of  the  Coastal  Plain,  on  the  Atlantic  coast,  the  soft,  loose  sedi- 
ments of  the  plain  rest  against  more  resistant  crystalline  rocks,  such  as  granites,  schists,  and 
gneisses.  The  rivers  of  this  region  flow  down  across  these  hard  rocks,  and  then  on  to  the  soft 
strata  of  the  Coastal  Plain.     In  which  of  these  classes  of  rock  can  streams  erode  the  more 

rapidly?     Why  would  the  •"  Fall  Line" 

(as  this  contact  line  of  the  hard  and  soft  rocks  is  called)  be  an  especially  favorable  site  for 

129 


the  growth  of  cities  ?. 


Make  a  list  of  the  important  cities  located  along  the  "Fall  Line,"  and  the  river  on  which  they 
are  situated.     


On  your  contour  map  of  the  United  States  color  in  lightly,  with  yellow  pencil,  the  area  of 

the  Coastal  Plain  regions.     Fill  in  a  legend  square  (with  yellow  pencil  also)  as  indicated  on 

the  diagram  map  (Fig.  21)  and  mark  it  Coastal  Plains. 

Study  of  a  The  Winterville  (N.C.)  sheet  presents,  in  detail,  typical  conditions  of  the  Coastal  Plain 

typical  sec-  area.    Locate  and  plot  the  area  of  this  sheet  on  your  United  States  map,  outlining  it  with  ink. 

tion  of  the     Letter  or  write  in  the  name  of  the  sheet. 

C  03.  S  tell 

plain                    What  would  be  the  surface  topography  of  a  coastal  plain  just  after  it  was  lifted  above  the 
sea?      


What  has  happened  to  this  part  of  the  plain  since  its  uplift  above  the  sea  ? 


What  areas  have 

conditions  resembling  the  original  surface?     

What  do  such  divides  between  streams  indicate 

as  to  the  age  of  the  region  where  they  occur  ?      

[ What  is  the  contour  interval  of  this  sheet  ? 

What  is  the  present  average  elevation  of  the  region  above  the  sea 

level  ?     

130 


Profile  of  a  Make  a  longitudinal  profile  (in  the  manner  directed  in  exercise  No.  XXV)  of  the  valley 

Coastal         0f  Hardee  Creek  from  its  mouth  at  the  Tar  River  to  its  source.     Where  is  the  slope  of  the 
^Plain 

^^^         '         valley  greatest,  near  its  mouth  or  its  source?     

What  does  this  indicate  as  to  the  kind  and  position  of  the  erosion  which  the  stream  is 

accomplishing?     


How  deep  is  this  valley  at  a  point  about  two  miles  from  its  mouth? 

How  wide? 

What  form  of  cross  section  has  it?      

i_    How  will  this  cross  section  be  modified  as  time  passes  ? 


Comparison           What  similarities  in  valley  form  have  the  streams  on  this  sheet  with  those  of  the  Fargo 
with  drain- 
age condi-      sheet  ? 
tions  on 
other  young 
plains. 


What  differences  in  the  conditions  in  the  valley  bottoms  ? 


How  may  the  greater  elevation 

of  the  Fargo  region  help  to  account  for  the  less  swampy  conditions  on  it  ?      

What  is  the 

elevation  above  sea  level  of  the  major  portion  of  the  area  of  Donaldsonville,  Louisiana  sheet  ? 

How  does  the  amount  of  swamp  land  there 

compare  with  that  on  the  Winterville  sheet  ? 

What  similarity  in  the  nature  of  the  divides  exists  between  the  Fargo  region  and  the  Winter- 
ville Coastal  Plain  region? 


131 


Human  What  is  the  pattern  of  the  roads  on  the  Winterville  sheet  as  compared  to  the  Fargo  sheet  ? 

occupation. 

Is  this  difference  wholly  or  partly  due  to  a  difference  in  topography  ? 
What  areas  do  the  roads  on  the  Winterville  sheet  especially  avoid  ? 

On  comparing  the 

courses  of  the  railroad  lines  and  the  wagon  roads  on  the  Winterville  sheet,  what  reasons  can 
you  suggest  for  the  greater  irregularity  of  the  wagon  roads?     


How  does  the  density  of  population  in  this  area  compare  with  that  indicated  on  the  Fargo 
sheet  and  the  Donaldsonville  sheet?     

How  do  you  account  for  the  difference  ?     


What  do 

such  place  names  as  "  Green's  Mill  Run,"  "  Harris  Mill  Run,"  "  Plank  Road,"  "  Gum  Swamp," 
and  the  comparative  sparseness  of  the  population  suggest  as  to  the  industry  of  the  region  ? 


Write  a  short  paragraph  summarizing  the  topographic  conditions  which  characterize  the 
Coastal  Plains  province  and  the  nature  of  its  settlement. 


132 


XXXI.  —  THE  GREAT  PLAINS 


Materials.  For  Each  Student.  —  Contour  map  of  the  United  States.    Mt.  Carrizo   (Col.)  sheet,  Syracuse 

(Kan.)  sheet,  Kearney  (Neb.)  sheet.    Colored  pencils. 

Purpose.  To  study  the  development  of  topography,  and  its  influence  on  settlement,  in  a  region  of  high 

plains  which  has  an  arid  climate. 


Introduc- 
tory. 


Location 
and  extent 
of  the  Great 
Plains. 


The  plains  studied  in  the  preceding  exercises  were  of  comparatively  low  elevation,  and  in 
a  humid  climate.  The  Great  Plains  region  has,  in  general,  a  much  greater  elevation  and  a 
much  more  arid  climate.  The  rocks,  however,  are  similar  in  origin  and  position  to  those  of 
the  Coastal  Plains,  —  that  is,  they  are  sediments  laid  down  in  former  seas,  and  still  lie  in 
nearly  horizontal  position ;  but,  being  more  firmly  consolidated,  they  are  more  resistant  to 
denudation  than  the  rocks  of  the  Coastal  Plains.  Therefore,  in  the  Great  Plains  we  study  the 
topography  resulting  when  a  region  of  plains  has  been  subjected  to  a  marked  uplift,  and 
exposed  to  the  agents  of  weathering  and  erosion  in  an  arid  climate;  also,  the  effects  of  such  a 
climate  on  the  human  occupation  of  the  region.     (Text-book,  pp.  77,  326-327.) 

On  your  contour  map  of  the  United  States  outline  the  area  of  the  Great  Plains,  as  shown 
on  the  diagram  map  (Fig.  21).     What  meridian  marks  the  general  eastern  limit  of  the  Great 

Plains?     What    determines    their     western 


boundary?     What  is  their  approximate  ele- 
vation above  the  sea,  as  shown  by  the  contour  lines  on  the  United  States  contour  map  ? 

How  does  this  compare  with  the  elevation  of 


the  Coastal  Plains  ? 


Parts  of  what  states  are  included  in  the  area  of  the  Great  Plains  ? 


• 


How  do  the  Great  Plains  compare  in  extent  with  the  regions  previously  studied  ? 


What  is 

the  general  industrial  and  agricultural  development  of  the  Great  Plains,  as  indicated  by  the 
number  of  important  cities  on  them,  and  as  compared  in  this  respect  wifh  the  regions  previ- 
ously studied?     


133 


Color  in  lightly  (with  brown  pencil)  the  area  of  the  Great  Plains  as  you  have  outlined  it 

on  your  United  States  contour  map.     Also  color  in  a  legend  square  with  brown,  and  mark  it 

Great  Plains. 

Study  of  Locate  the  position  of  the  Mt.  Carrizo  (Col.)  sheet  on  the  United  States  map  and  outline 

typical  with  ink  the  area  it  includes.     Also  letter  or  write  in  the  name  of  the  sheet  on  the  map. 

areas  of  the 

Great  Near  which  border  of  the  Great  Plains  is  this  area  located  ?     

Plains. 

What  is  the  elevation  of  this  border  as  compared  to  the  Mississippi 

Valley  in  the  same  latitude  ?      

What    average  slope   (approximately)  would   this   give  to 

streams  flowing  toward  the  east  ?    

How  would  such  a  slope  affect  their  power  of  erosion? 


Topog-  Make  a  cross  section  along  a  line  extending  from  a  point  2  inches  southeast  of  the  last 

raphy  of        «  a  "  in  Animas,  through  the  "  z  "  in  Mt.  Carrizo,  and  continuing  for  3£  inches  in  the  same 
the  western  diction.     Use  the  same  horizontal  scale  as  that  of  the  map,  and  let  one  division  of  the  cross- 
section  paper  equal  one  hundred  feet  in  the  vertical  scale. 

What  is  the  nature  of  the  stream  valleys  as  shown  by  this  cross  section  ?  


What  does  the  fact  that  the  streams  are  marked  by  dotted  blue  lines  indicate  ?  (See  Fig.  20.) 
If  after  a  long  dry  period,  a  heavy  rain  occurred,  why  would  the  water  drain  off  quickly  ? 

What  would  be  the  effect  of  this  rapid  run-off  on 

the  stream  valleys?  

Why  would  erosion  be  more  effective  than  weathering  in  this  region?    . 

134 


What  is  the  topogra- 
phy of  the  divide  areas  between  streams  ? 

Describe  the  shape,  slopes,  and  top  of  Mount  Carrizo  as  shown  by  the  map  and  your  cross 
section.      


Is  it  a  true  mountain  ? What  kind  of  a  land  form  is  it  ?  

Why  do  mesas  develop  extensively  in  arid  and  not  in  humid  regions, 

even  though  both  have  horizontal  strata?   


What  is  the  difference  between  a  butte  and  a  mesa 

as  illustrated  in  Potato  Butte  and  Fowler  Mesa?  


Human  Some  habitations  are  undoubtedly  located  in  this  area,  but  they  are  not  shown  on  this 

occupation     map.    What,  however,  does  the  small  number  of  roads  indicate  as  to  the  extent  of  settlement  ? 
along  west- 

What  two  conditions  would  prohibit  dense  set- 
tlement in  this  region  ?   


Topog-  Locate  the  position  of  the  Syracuse  (Kan.)  sheet  on  the  United  States  map  and  outline 

raphy  of       with  ink  the  area  it  includes.     Also  letter  or  write  in  the  name  of  the  sheet  on  the  map. 

the  Central  What  reasons  can  you  suggest  why  the  southern  part  of  this  area  is  much  less  dissected 


Great 
Plains. 


than  the  Mt.  Carrizo  region? 


Make  a  cross  section  of  the  country  on  a  line  between  Gognac 

in  the  southeast  corner,  and  Edwin  about  twelve  miles  to  the  northwest.    What  is  the  general 

topography  of  the  country  as  shown  by  this  cross  section  ? 

135 


This  is  typical  of  wide  expanses 

of  the  Great  Plains.    Why  is  there  much  greater  dissection  in  the  northern  part  of  the  sheet  ? 


What  effect  has  this  greater  dissection  on  the  course  of  the  roads?    

What  is  the  significance 

of  the  small  areas  inclosed  by  saw-edged  brown  lines  (Fig.  20)  ?    


Human  How  does  this  region  compare  in  density  of  population  (as  indicated  by  roads  and  towns) 

occupation 

in  Central      witn  that  of  the  Mt.  Carrizo  region  ? 

Great 

What  does  the  scattered  location  of  the  houses  suggest  as 

to  the  agricultural  possibilities  of  this  region  ?    

What  curious  relation  do  you  note  regarding 

the  number  of  houses  and  streets  in  the  towns  of  Johnson  and  Kendall  ? 


Topog-  Locate  the  position  of  the  Kearney  (Neb.)  sheet  on  the  United  States  map,  and  outline 

raphy  of       with  ink  the  area  it  includes.     Also  letter  or  write  in  the  name  of  the  sheet  on  the  map. 

the  eastern  What  is  the  character  of  the  eastern  portion  of  Platte  River,  as  shown  by  this  map  ? 

border  of  r  '  * 

the  Great 

Plains.  


What  causes  this  braided  channel  condition  ? 


What  is  the  source  of  the  sediment  supply  ? 


Why  is  it  deposited  in  this  eastern  portion  of  the  river?  

What  is  the  nature  of  the  topogra- 


136 


phy  to  the  north  of  the  Platte  River  ?   

To  the  south? 


These  numerous  depressions  and  small, 

low  summits  are  the  topography  of  a  sandhill  area.     What  is  the  source  of  the  sand  supply  ? 


What  must  be  the  prevailing  wind  direction?    

Human  What  difference  is  shown  on  this  sheet  in  the  extent  of  continuously  flowing  streams 

occupation 

o  eastern      ag  compare(j  to  those  of  the  Central  and  Western  Great  Plains  areas  ?  

border.  r 


What  does  this  indicate 

as  to  the  difference  in  climate  from  west  to  east?     

What  is  the  effect  of  this  difference  in 

climate  on  the  density  of  settlement?  

What  difference  in  the  nature  of  agricultural  industry, 

in  the  western  and  eastern  parts  of  the  Great  Plains,  does  this  difference  in  density  of  popula- 
tion indicate?    


Write  a  short  paragraph  summarizing  the  origin  and  nature  of  the  topography,  and  the 
human  occupation  of  the  Great  Plains  region. 


137 


* 


( 


XXXII.— THE  APPALACHIAN  PLATEAU 


Materials. 


Purpose. 


Introduc- 
tory. 


Location 
and  extent 
of  the 
region. 


For  Each  Student.  —  The  contour  map  of  the  United  States.  The  Centerpoint  (W.Va.)  sheet. 
Colored  pencils. 

For  General  Class  Use.  —  The  Mt.  Carrizo  (Col.)  sheet. 

To  study  the  topography  and  settlement  in  a  region  of  elevated  horizontal  strata  (a  high  plain 
or  plateau)  where  the  climate  is  humid,  and  ivhich  has  been  denuded  for  a  long  period. 

The  Appalachian  Plateau  bears  the  same  relation  to  the  Appalachian  Mountains  that  the 
Great  Plains  do  to  the  Eocky  Mountains,  —  that  is,  the  Appalachian  Plateau  is  a  region  of 
elevated,  horizontal  strata,  located  on  the  inland  side  of  the  Appalachian  Mountains.  The 
Appalachian  Plateau  contrasts  with  the  Great  Plains  in  that  it  lies  in  a  humid  climate,  has 
been  denuded  longer,  and  is  made  up  of  harder  rocks  than  the  Great  Plains.  (Text-book, 
p.  84.) 

On  your  contour  map  of  the  United  States  outline  the  area  of  the  Appalachian  Plateau, 
as  shown  on  the  diagram  map  (Fig.  21).     What  is  the  size  of  this  region  as  compared  to  that  of 

the   Great  Plains?     What  parts  of  what 

states  are  included  in  it?     

• What  is  the  approximate  elevation  of  the  Appalachian  Plateau? 

How  does  this  compare  with  the  Great  Plains 

region  ? 


Color  in,  with  ruled  brown  lines  (as  indicated  by  the  pattern  of  the  legend  square  on  the 
diagram  map,  Fig.  21),  the  area  of  the  Appalachian  Plateau  as  you  have  outlined  it  on  your 
United  States  contour  map.     Add  the  proper  legend  square,  and  mark  it,  Appal.  Plat. 
Study  of  a  Locate  the  position  of.  the  Centerpoint  ( W.  Va.)  sheet  on  the  United  States  map  and  out- 

typical  sec-  iine  with  ink  the  area  it  includes.     Also  letter  or  write  in  the  name  of  the  sheet. 
tion  of  the  get  (jown  the  height  of  ten  different  hill   summits  from  different  parts  of  the  sheet. 

chian 

Plateau.         

a 

139 


How  do  they  compare  in  height? 


If  the  valleys  were  all  filled  in,  what  would  be  the 

appearance  of  this  region  ? 

What  was  the  original  topography  of  this  region  as  suggested 

by  the  uniform  height  of  the  hills  ?     


What  has  taken  place  since? 


Make  a  cross  section  along  a  line  running  northwestward  between  the  towns  of  Cascara 
and  Roberts.  Use  the  same  horizontal  scale  as  that  of  the  map,  and  let  one  division  of  the 
cross-section  paper  equal  sixty  feet  in  the  vertical  scale.  (This  will  give  a  cross  section  com- 
parable (nearly)  to  the  one  made  of  the  Great  Plains.)  In  making  this  cross  section  it  will 
not  be  necessary  to  mark  all  the  intersections  of  the  contour  lines ;  those  showing  the  eleva- 
tion of  the  hilltops  and  the  valley  bottoms  will  be  sufficient  to  give  good  results. 

What  is  the  form  of  the  valley  cross  sections  in  this  region  as  compared  with  those  of  the 


Great  Plains  ? 


How  do  the  divides  between  streams  compare  in  form  in  the  two  regions  ? 


What   is   the   age   stage   of    a    region   which    has   V-shaped   valleys    and    ridge    divides  ? 

Is  this  a  more  arid  or  more  humid  region 

than  the  Great  Plains?     Why  would  greater 

humidity  accelerate  weathering  and  the  formation  of  ridge  divides?     


140 


Human  What  determines  the  course  of  the  roads  in  this  region  ? 

occupation. 


Why  is  this  the  case  ? 


Where  are  the  houses  and  towns  located  ?     

Why  are  there  so  few  houses  on  the  ridges  and 
the  valley  slopes?     

Would  this  region  be  easier  or  more  difficult  to  cross  than  the  Great 

Plains  region  ?    If  transportation  is  so  much 

more  difficult,  why  is  there  a  so  much  greater  population  than  in  that  part  of  the  Great  Plains 

that  lies  near  the  mountains  ?     


Why   do    extensive   forests   still   remain   in    this    region  ? 


Where  the  forest  is  cleared  off  is  the  land  better  suited  to  sheep  raising  or  the  raising  of  crops  ? 

What  would  be  the  effect  of  the  discovery 

of  coal  or  iron  on  the  settlement  of  such  a  region  as  this?     


Write  a  short  paragraph  describing  a  plateau  region  in  a  humid  climate  having  mature 
drainage  conditions ;  and  tell  why  such  a  region  is  difficult  of  settlement  and  development. 


141 


XXXIII.  — THE   CENTRAL   PLAINS   REGION 

Materials.  For  Each  Student.  —  The  contour  map  of  the  United  States.    Caldwell  (Kan.)  sheet,  Fargo 

(N.D.)  sheet,  Centerpoint  (W.Va.)  sheet.    Colored  pencils. 

Purpose.  To  study  a  plams  region  in  which  the  erosion  cycle  has  advanced  to  the  old  age  stage. 

Introduc-  The  Fargo  and  Centerpoint  sheets  are  typical  of  plains  regions  in  which  the  topography 

tory.  and  drainage  conditions  are  respectively  young  and  mature.     The   Caldwell  sheet  of  the 

Central  Plains  province  typifies  a  plains  region  where  the  erosion  cycle  has  continued  until 

the  country  has  acquired  the  characteristics  of  a  plains  region  in  old  age.     Thus  the  three 

regions,  of  which  these  sheets  are  typical,  illustrate  the  stages  in  the  development  of  plains 

topography  from  youth  to  old  age.     (Text-book,  pp.  76-78  and  310-314.) 

Location  On  your  contour  map  of  the  United  States  outline  the  area  of  the  Central  Plains  province 

and  extent     as  shown  on  the  diagram  map  (Fig.  21).     What  proportion  of  the  area  of  the  United  States 
of  the  Cen- 

province        ^oes  tQis  re^on  constitute?     fc What  is  its 

approximate  elevation   above   sea  level?    

What  large  cities  are  located  in  the  Central  Plains  province?     

What  reasons  can  you  give  to  account  for  the  great  importance  of  this  region  in  the  develop- 
ment of  the  country?     

What  is  the  general    slope  of   the  region? 

What  are  its  secondary  slopes?     

Color  in,  with  ruled  blue  lines,  (as  indicated  by  the  pattern  of  the  legend  square  on  the 
diagram  map,  Fig.  21),  the  area  of  the  Central  Plains  region  as  you  have  outlined  it  on  your 

143 


United  States  contour  map.     Also  add  the  proper  legend  square  and  mark  it  Central  Plains 

region. 
Study  of  a  Locate  the  position  of  the  Caldwell  (Kan.)  sheet  on  the  United  States  map,  and  with  ink 

typical  sec-  outline  the  area  it  includes.     Letter  in  the  name  of  the  sheet. 
tion  of  the  In  wlmt  part  of  the  Central  Plains  is  this  area  located  ? 

Central  —————— 

Plains  in 

the  south-     Judging  by  your  previous  study  of  regions   to  the  east  and  west  of  the 

era  part. 

Central  Plains,  would  this  area  have  more  or  less  rainfall  than  parts  of  the  Central  Plains  to 

the  east?     What  indications  of  light  rainfall 

do  you  find  on  the  Caldwell  sheet?    

What  indications  are  there,  however,  that  the  rainfall 

is  sufficient  for  successful  agriculture?     

How  many  square  miles  of  land  are  shown  on  the  Caldwell  sheet?     

What  is  the  highest  point  on  the  sheet?     

The  lowest?     What  is  the  average  direction  of  slope ?     

.__ Whatthen 

is  the  general  topography  of  the  area  ?     


Make  a  cross  section  (along  a  north-south  line)  between  the  station  Doster,  on  the 
St.  Louis,  Kansas,  and  Southwestern  Railroad,  and  the  Sante  Fe  Railroad.  Use  the  same 
horizontal  scale  as  that  of  the  map,  and  let  one  section  of  the  cross-section  paper  equal  forty 
feet  vertical  scale. 

Make  a  profile  of  Pall  Creek  from  its  intersection  with  the  St.  Louis,  Kansas,  and  South- 
western Railway  to  its  source,  using  the  same  vertical  scale  as  in  the  cross  section. 

What  are  the  shapes  of  the  valley  cross  sections?     

How  do  they  differ  from  those  of 

the  Fargo  sheet?     


How    are    they   different    from    those   of   the   Centerpoint    sheet  ? 
144 


How   do  these  three  regions  compare  as   to  the  amount  of  elevation   above   sea  level  ? 


By  what  processes  of  denudation  might  the  valleys  of  the  Centerpoint  sheet  be  modified  so 
that  they  would  resemble  those  of  the  Caldwell  sheet? 


Would  a  long  time  or  a  short   time, 

physiographically  speaking,  be  required  to  bring  about  such  a  modification?     

Why  are  there  no  swamps  in  the  stream  bottoms  of  the  Caldwell  sheet,  although  the 

stream  courses  are  meandering? L 

What  is  meant  by  saying  that  a  stream  has  reached  grade  ? 


What    is    the    character    and    outline    of    the    divides    between    the    streams  ? 


How  do  these  differ  from  those  of  the  Fargo 

sheet,  on  the  one  hand,  and  the  Centerpoint  sheet  on  the  other? 


Diagram   the   pattern  of 

145 


the  drainage  system  on  the  Caldwell  sheet,  showing  how  a  large  stream  is  fed  by  tributaries, 
and  these  in  turn  by  smaller  tributaries,  and  so  on. 


Why  is  such  a  drainage  system  called  dendritic?     

1 Is  the  angle  between 

a  tributary  and  a  main  stream  acute  or  obtuse  on  the  upstream  side?     

What  are  the  conditions  on  the  Fargo  sheet  in  this  respect?      


Human  What  is  the  pattern  of  the  wagon  roads  on  the  Caldwell  sheet  ? 

occupation. 

Why  is  such  a  pattern  possible  here  ?     . 


Do  the   railways   attempt  to  follow   the   lines   of   the   divides   or  of   the  stream   valleys  ? 

Are  the  bends  in  the  course  of  the  Wichita 

and   Western   division   of    the   Missouri-Pacific   Railroad   necessitated   by  the   topography, 


or  by  a  desire  to  touch  at  every  small  town  ? 


.__     Why  would  such  a  course  be  impossible  on 
146 


the  Appalachian  Plateau  ? 


What  determines  the  location  of  towns  in  the  region  of  the  Caldwell  sheet  ? 


Why  have  some  towns  grown  to  a  larger  size  than  others?     

No  houses  are  plotted  on 

this    sheet.     Would    you     infer     from     this     that     this   is    a     sparsely    settled     region? 

What  do  the  number  of  small  towns,  the  number  and  pattern 

of   the   roads,   and   the   number   of  railroads   indicate   in  this   connection?     


Write  a  short  paragraph  comparing  and  contrasting  the  topography,  drainage,  and 
human  occupation  in  plains  regions  in  youth,  maturity,  and  old  age,  as  studied  in  this  and 
the  preceding  exercises. 


147 


c 


XXXIV. —THE  AREA  OF  CONTINENTAL  GLACIATION  IN  THE  UNITED  STATES 


Materials. 


Purpose. 


Introduc- 
tory. 


Location 
and  extent 
of  the  area 
of  conti- 
nental gla- 
ciation  in 
the  United 
States. 


For  Each  Student.  —  The  contour  map  of  the  United  States.  The  Whitewater  (Wis.)  sheet, 
the  Caldwell  (Kan.)  sheet. 

To  gain  an  appreciation  of  the  area  of  the  United  States  that  was  affected  by  the  continental 
glacier  daring  the  glacial  period;  and  to  study  a  portion  of  the  glaciated  area  where  the  effects  of 
the  ice  advance  and  retreat  were  very  pronounced. 

In  the  preceding  exercises,  plains  regions,  whose  structure  was  in  every  case  horizontally 
bedded  sediments,  have  been  studied  to  bring  out  the  variation  in  their  topography  and  devel- 
opment as  dependent  on  their  age,  their  elevation,  and  their  location  in  a  humid  or  arid  climate. 
The  erosion  cycle  in  each  of  the  regions  thus  far  studied  may  be  considered  as  having  con- 
tinued uninterruptedly.  However,  it  may  happen  that  what  can  be  termed  an  unexpected 
factor  is  introduced  at  some  stage  in  this  cycle ;  and,  in  that  case,  the  drainage  of  the  region 
is  said  to  have  suffered  an  accident.  Such  an  accident  was  the  occurrence  of  the  period  of 
continental  glaciation  in  northern  United  States. 

In  regions  where  the  topography  was  irregular  and  well  defined,  as,  for  example,  in  moun- 
tainous or  dissected  plateau  regions,  the  effect  of  the  glaciation  was  not  of  a  dominating  char- 
acter on  the  appearance  of  the  region  as  we  know  it  to-day.  On  regions  like  the  Central 
Plains  area,  on  the  other  hand,  which  had  advanced  to  the  gentle  relief  of  an  old-age  stage,  the 
effect  of  the  glacial  advance  was  very  marked  and  striking.  (Text-book,  pp.  148-149  and 
154-156.) 

The  line  of  dashes  and  circles  on  the  diagram  map  (Fig.  21)  marks  the  outline  of  the 
greatest  extension  of  the  ice  sheet  of  the  Wisconsin  advance  of  the  continental  glacier.  Plot 
this  outline  in  ink  on  your  contour  map  of  the  United  States,  using  the  same  symbols.  Fill 
in  also  a  legend  square,  as  indicated  on  the  diagram  map  (Fig.  21). 

Where  did  the  continental  glacier  advance  farthest  south?      


What  effect  did  the  presence  of 

the  Appalachian  Plateau  have  on  the  advance  of  the  ice  in  the  eastern  part  of  the  United 

States?     

Why  did  the   region   around   the  western   end  of   Lake   Superior   have  a   similar   effect? 

What  comparison  can  you  make  regarding  the  number  of  lakes  within  and  outside  the  area 
of  glaciation  ?     

149 


What  suggestion  as  to  the  origin  of  the  basin  of  Lake  Michigan  do  you  find  on 

comparing  the  direction  of  its  extension  and  that  of  the  ice  lobe  that  covered  this  region  ? 


To  which  of  the  other  Great  Lakes  might  this  explanation  be  also  applied  ? 


Is    the    region    of 

densest  population  of  the  United  States  within  or  outside  of  the  area  of  continental  glaciation  ? 


Study  of  a  The  Whitewater  (Wis.)  sheet  illustrates  conditions  which  are  more  or  less  common  in 

section  of  ^a^  par^  0f  ^e  Central  Plains  within  the  area  of  continental  glaciation.     Locate  the  position 

Plains  ela-  °^  *^e  sheet  on  your  United  States  map,  and  outline  its  area  with  ink.     Letter  or  write  in  the 

ciated  area.  name  of  the  sheet- 

Is  there  any  system  to  the  topographic  features  shown  on  this  sheet  ?     

What  is  the  condition  of  the  drainage  of  the  area  ?     


Have  the  streams  any  general  direction  of  flow?     How  can  these  drainage 

conditions  be  accounted  for  by  assuming  the  former  presence  of  a  great  ice  sheet  ?     


What  would  be  the  effect,  on  a  region  in  an  old-age  stage  of  development,  of  dumping  great 
masses  of  debris  without  regard  to  order  or  system  in  arrangement,  or  amount  deposited,  in 

any  one  place? : 


150 


Why  is   the   drainage  system  in  a  glaciated  area  said   to   have  suffered   an   accident? 


What  is  the  origin  of  the  many  lakes  ? 


The  band  of  low  hills  and  depressions  which  extends  across  the  southeastern  portion  of 
the  sheet  is  a  terminal  moraine.  Make  a  cross  section  of  it  on  a  line  between  the  northern 
end  of  Lauderdale  Lake  and  the  word  "  Prairie  "  of  the  Prairie  du  Chien  division  of  the  Chi- 
cago, Milwaukee,  and  St.  Paul  Railroad.  Let  one  section  of  the  cross-section  paper  equal 
twenty  feet  in  the  vertical  scale. 

Describe  the  topography  of  a  moraine  ridgeUs  shown  by  this  cross  section. 


What  is  the  cause  of  the  small  lakes  and  ponds  on  the  moraine  ridge  ? 


Human  What  pattern  of  roads  was  attempted  in  this  area  ? 

occupation. 

What  features  interfered  with  carrying  it  out?     


What  reasons  seem  to  justify  the  building  of  wagon  roads  across  the  large  swamps  ? 


• 


How  are  the  courses  of  the  roads  affected  in  crossing  the  moraine  ridge  ? 


How  could  large  areas  of  this  region  be  reclaimed  for  agricultural  purposes  ? 


151 


XXXV. —A   REGION   OF   DRUMLINS 

Materials.  For  Each  Student.  —  The  contour  map  of  the  United  States.     The  Weedsport  (N.Y.)  sheet. 

Purpose.  To  study  a  striking  topographic  phenomenon  due  to  continental  glaciation. 

Introduc-  Over  several  large  areas  within  the  region  of  continental  glaciation  in  the  United  States 

tory-  {e.g.  in  Massachusetts,  New  York,  and  Wisconsin),  the  ice  sheet  produced  remarkable  clusters 

of  low  hills,  to  which  the  name  drumlin  has  been  given.     Their  height,  shape,  and  alignment 

afford  evidence  as  to  the  direction  and  nature  of  the  ice  movement.     So  far  as  known  the 

drnmlins  are,  in  the  main,  composed  of  unstratified  clay  and  bowlders,  called  till.     (Text-book, 

pp.  152-153.) 

Study  of  a  The  Weedsport  (N.Y.)  sheet  shows  a  typical  drumlin  area.     Locate  this  area  on  your 

drumlin         United  States  map,  and  outline  it  with  ink.     Letter  or  write  in  the  name  of  the  sheet  beside 

area.  ^he  rectangle. 

What  is  the  most  striking  topographic  feature  of  this  sheet?  

What  is  the  pattern,  or  arrangement,  of  the  many  hills  ?  

What  is  their  general  compass  direction?  

What  would  you  infer  from  the  arrangement  and  development  of  the  drumlin  hills  as  to  the 

direction  of  movement  of  the  ice  mass  which  made  them  ? 

How  do  the  drumlins  influence  courses  of  streams  ?  

Study  of       Are  the  lakes  and  swamps  in  this  area  due  to  the  presence  of  the  drumlins  ? 

•    individual 
drumlins.  Draw,  freehand,  small    longitudinal   profiles  and  width  cross  sections  of  a  number  of 

drumlins  in  the  space  provided  on  the  next  page. 

153 


On  which  end  have  they  the  steepest  slopes?  What  variation  is  there 

in  the  slope  and  shape  of  the  other  end?  


Does  the  slope  of  the  two  sides  also  vary  in  any  one  typical  drumlin  ? 

What  is  the  height  (from  base  to  top)  of  six  different  drumlins  on  different  parts  of  the 

sheet  ?     


What  is  their  average  height  ?  What  is  their  average  width  ? 

How  do  they  vary  in  length?   


Human  Why  would  tillage  be  difficult  on  all  parts  of  drumlins  ? 

occupation. 


What  conditions  interfere  with  agricultural  pursuits  in  many  of  the  depressions  between  the 

drumlins? How  have  the  drumlins  affected 

the  courses  of  the  wagon  roads  and  railroads? 


154 


Materials. 
Purpose. 

Introduc- 
tory. 


General 
features  of 
the  Niagara 
River. 


Upper 
Niagara. 


Lower 
Niagara 
River  and 
the  Niagara 
Escarp- 
ment. 


• 


XXXVI.  — THE   NIAGARA   REGION 

For  Each  Student.  —  The  Niagara  Falls  and  vicinity  sheet,  published  1901. 

To  study  the  course  and  physiographic  relations  of  the  Niagara  River. 

The  Niagara  River  is  a  stream  which  owes  its  existence  to  the  effects  of  the  continental 
glacier.  Before  the  glacial  period  the  drainage  of  this  region  was  of  an  altogether  different 
nature,  and  there  was  then  no  important  stream  having  the  course  of  the  present  Niagara. 
Therefore  the  Niagara  River  may  be  studied  as  a  young  river  whose  course  is  due  to  the  acci- 
dent of  glaciation.     (Text-book,  pp.  330-334.) 

What  is  the  source  of  the  Niagara  River  ?     

Where  is  its  outlet?     What  is  its  approximate 

length?     What  is  its  average  width  (considering  both  arms)  above 

the  Falls?      Below  the  Falls  ? 

In  which  part  must  it  be  deeper  and  more  rapid  ? _. 

What  is  the  topography  of  the  region  over  which  the  upper  Niagara  flows  ?     

Make  a  cross  section  on  a  line  between  Inland  and  Pull- 
man (near  Buffalo).     Let  one  section  of  the  cross-section  paper  equal  forty  feet  in  the  vertical 

scale.     What  is  the  nature  of  the  banks  of  the  upper  Niagara  River?     

How  does  this  cross  section  compare  with  that  of  the  Mississippi? 

Why  is  the  upper  Niagara  River  free  from  sediment  ?      

Why  is  it  free  from  floods?     

'. What  is  the  elevation  (approximate)  of  the  upper 

Niagara  Plain  (Erie  Plain)?     

What  is  the  elevation  of  the  Lower  Niagara  River  Plain  (Ontario  Plain)  near  Lewiston? 

By  wrhat  topographic  feature  are  the  two  plains  separated  ?     

How 

high  is  the  Niagara  Escarpment  ?     How  steep  is  its ,  slope  near  the 

Niagara  River?     

155 


In  what  direction  does  the  escarpment  extend  ? 


Make  a  cross  section  across  the  lower  Niagara  River  on  a  line  between 

Four  Mile  Creek  and  the  Michigan  Central  Railroad.     Use  the  same  vertical  scale  as  in  the 

cross  section  of  the  Upper  River.     How  do  the  two  cross  sections  compare  ? 


The  gorge  How  long  is  the  gorge  section  of  the  Niagara  River  ? 

section  of 

theNiagara   What  marks  the  limit  of  its  upstream  extension  ?       

River. 

What  marks  the  limit  of  its  downstream  extension  ?      

At  which  end  is  it  growing  longer?     

What  was  the  first  position  of  the  Falls  ?    (Text-book,  p.  332.)     

If 

the  cataract  receded  at  the  same  rate  as  at  present  (about  5  feet  per  year),  during  all  the 

period  of  its  existence,  how  long  did  it  take  to  cut  the  gorge?     

Why  are  hachures,  instead  of  contour  lines,  used  on  the  gorge  section  of  the 


Make  a  cross  section  of  the  gorge  (extending  two  miles  on  either  side)  on  a  line 
parallel  to  the  Niagara  Escarpment  and  one  mile  south  of  it.  Use  the  same  vertical  scale  as 
in  the  preceding  cross  section,  and  assume  that  the  gorge  is  as  deep  as  the  escarpment  is  high. 
Describe  this  cross  section  and  compare  it  with  those  of  the  upper  and  lower  Niagara  River. 


Why  is  the  river  so  much  narrower  in  the  gorge  than  on  either  plain  ? 


156 


What   evidence   is 

there  that  the  northwest  bank  of  the  Whirlpool  is  made  of  softer  material  than  other  parts  of 

the  gorge  wall  ?     


The  Falls.  How  high  are  Niagara  Falls  ? What  is  the 

outline  of  the  crest  of  the  Canadian  Falls?     _• 

The  American  Falls  ?     Why  has  the  Niagara 

Eiver  a  greater  sediment  load  below  than  above  the  Falls  ? 

In  what  way  does  the  presence  of  Niagara  Falls  and  Gorge  affect  navigation  ?     


How  does 

this  account  for  the  location  of  Buffalo  ? 


Why  is  there  not  a  city  of  equal  importance  at  the 

southern  end  of  Lake  Huron  ?     


Where  does  the  Erie  Canal  begin  ? . 


What  reasons  can  you 
give  for  the  location  of  Tonawanda  ? 


157 


Why  is  the  shipping  of  Lake   Ontario  of  less  impor- 
tance than  that  of  the  upper  Great  Lakes  ?      


Why  are  there  many  manufacturing  establishments  at  Niagara  Falls  City  ? 


How  will  the 

further  development  of  Niagara  power  affect  the  surrounding  region  ?      

What  other  reason 

can  you  give  for  the  location  of  a  city  at  Niagara  Falls  ?      


t 


158 


XXXVII.  —  PLAINS  CITIES  AND  THEIR  ENVIRONS 

Materials.  For  Each  Student.  —  The  Cleveland  and  Vicinity  sheet,  the  St.  Louis  sheet,  the  Denver  quadrangle. 

Purpose.  To  gain  an  appreciation  of  the  factors  which  influence  the  location  and  growth  of  cities,  and 

the  effect  of  the  cities  on,  and  their  response  to,  their  physiographic  environment. 

Introduc-      i        Cities  on  the  seacoast,  and  in  mountains,  which  grow  to  a  large  size,  owe  their  growth,  in 
tory-  the  main,  to  some  especially  favorable  factor  of  environment  which  dominates  all  other  dis- 

advantages the  site  may  have.     In  the  case  of  plains  cities,  however,  there  is  a  wider  variety 
of  possible  locations,  and  the  large  city  becomes  established  because  of  a  variety  of  interacting 
lesser  influences  combining  to  give  one  site  an  advantage  over  its  rivals.     (Text-book,  pp.  166, 
312,  315,  375-377.) 
Broad  Examine  the  topographic  sheets  for  the  cities  of  Cleveland,  St.  Louis,  and  Denver.     What 

relations.       jg  the  one  dominating  factor  which  made  possible  the  growth  of  Cleveland  and  St.  Louis  ? 


What  topographic  feature  prevented  the  growth  of  a  large  city  farther  to  the  west  than  is 

Denver  ? 

Why  are  transportation  conditions  of  such  supreme  importance  in  fixing  the  sites  of  great 

cities  ?    


What  are  the  chief  industries  of  cities  ?     

Of  what  advantage  is  it  to  a  city  to  have  a  rich 

agricultural  country  immediately  tributary  to  it? 


Cleveland  and  St.  Louis  ? 


How  would  this  fact  affect  the  growth  of  Denver  as  compared  to 


159 


Is  Denver  of  more  importance  as  a  commercial  center,  or  as  a 

manufacturing    center?     


Note  that  the  growth  of  Denver  has  been  a  radial  one, — that  is,  from  the  center  outwards. 
What  is  the  significance  of  this'  in  regard  to  the  favorableness  for  habitation  of  the  surround- 


ing area? 


Cleveland  has  grown  outwards  from  the  diameter  of  a  circle.     What  reasons  can  you  assign 
for  this  fact?     


Why,  on  the  other  hand,  has  the  growth  of  St.  Louis  been  focused  on  the  circumference  of  a 
circle  ? 


What  are  the  two  great  interior  waterways  of  the  United  States  ? 


On  which  of  these  is 

St.  Louis  located?     Cleveland?     

What  advantage  has  Cleveland  with  regard  to  the  location 

of  the  eastern  coalfields  which  enables  it  to  compete  with  Chicago  ?     


Why  can  St.  Louis 

successfully  compete  with  Chicago  in  marketing  her  manufactures  in  the  Southern  States  ? 


160 


What  is  the  elevation  of  the  land  on  all  sides  of  Denver  as  compared  to  the  site  of  the  city 
itself  ? What  advantage  does  such  a  site  offer 

m 

^^  as  compared   to  the  adjacent   areas?     


Exact  Why  is  St.  Louis  located  on  the  west,  and  not  on  the  east  side  of  the  river  ? 

location. 


Why  have  no  extensive  suburban  districts  been  built  on  the  east  side  ? 


What  was  the  influence  of  the  Cuyahoga  Kiver  in  determining  the  exact  site  of  the  early 
Cleveland?     , „ 

Why  has  the  city  grown  more  to  the  east  and  west  than  to  the  south  ?     


What  advantage  does  Denver  derive  from  being  on  the  South  Platte  River  ? 


What  advantage  from  being  near  the  base  of  the  mountains  rather  than  farther  out  on  the 
plains  ?    ! 


Environs  of  What  effect  has  the  presence  of  a  city  on  the  direction  of  the  main  roads  in  the  surround- 

cities. 

ing  region  ?     


161 


OF   THE 

UNIVERSITY 


Which,  St.  Louis  or  Cleveland,  is  the  objective  point  of  the  greatest  number  of  railway  lines  ? 

What  does  this  suggest  as  to  the  relative 

importance  of  railway  transportation  to  the  commerce  of  these  two  cities  ? 


From  what  directions  do  most  railway  lines  enter  Denver?      ^ 

Why  so  few  from  the  west? 

Why  are  there  generally  many  short  roads,  numerous  houses,  and  small  towns  in  the 
immediate  vicinity  of  large  cities?     


What   is   the    nature    of    the    agricultural    products    raised    on    farms    near    large    cities  ? 


What  is  the  significance  of  the  many  short,  canal-like  branches  which  extend  from  Clear 
Creek  and  Ealston  Creek  near  Denver? 


Write  a  short  paragraph,  stating  some  of  the  important  factors  which  influence  location 
and  growth  of  large  cities,  and  the  effect  of  the  presence  of  the  cities  on  the  surrounding 

country.     


162 


Materials. 


Purpose. 


Introduc- 
tory. 


Location 
and  extent 
of  the 
Folded  Ap- 
palachians. 


XXXVIII.— THE   FOLDED   APPALACHIANS 

For  Each  Student.  —  The  contour  map  of  the  United  States.  The  Monterey  (Va.-W.Va.) 
sheet,  the  Delaware  Water  Gap  (Pa.-N.J.)  sheet.     Colored  pencils. 

To  study  a  mountain  region  ivhose  topography  is  the  result  of  the  upfolding  of  sedimentary 
rocks,  and  their  later  denudation. 

True  mountains  are  either  regions  where  rocks  which  were  once  horizontal  have  later  been 
folded,  faulted,  and  metamorphosed ;  or  regions  in  which  the  rocks  are  crystalline  in  character, 
and  generally  with  a  very  complex  structure.  These  crystalline  rocks  often  constitute  a  core 
underlying  mountains  made  of  folded  sediments,  and  are  exposed  to  weathering  and  denuda- 
tion only  after  the  overlying  masses  have  been  worn  away. 

The  Appalachian  mountains  are  interesting  in  that  they  include  both  types :  (1)  moun- 
tains composed  of  folded  sediments;  and  (2)  mountains  which  are  made  up  wholly  of  crystal- 
line rock.  Moreover,  the  most  eastern  belt  of  the  Appalachians  consists  of  crystalline 
mountains  which  have  been  worn  down  until  only  their  roots  remain,  and  their  surface  resem- 
bles a  plain  in  topography. 

This  exercise  is  a  study  of  the  western  belt  of  the  Appalachian  Mountains,  which  are 
made  up  of  folded  and  then  denuded  sedimentary  strata.     (Text-book,  pp.  101-105.) 

Figure  21  shows  the  province  of  the  Folded  Appalachians,  marked  "  Folded  Appalachians." 
Plot  the  outlines  of  the  Folded  Appalachians  on  your  contour  map  of  the  United  States. 

What  parts  of  what  states  are  included  in  this  province?     


What  is  the  general  trend  of  these  mountains?     

How  do  you  account  for  the  fact  that 

they  do  not  appear  in  the  Mississippi  Valley,  but  reappear  in  Arkansas?     


Estimate  the  length 

of  the  whole  system.     What  is  its  average 

width?     What  proportion  of  the  area  of  the 

United  States  east  of  the  Mississippi  do  the  Folded  Appalachians  constitute  ?    

163 


Appalachian  Ridges  on  the  Monterey  (Va.-W.Va.)  Sheet 
On  a  Line  from  Southeast  to  Northwest  across  the  Map 


No. 

Namk  of  Ridge 

Elevation 

No. 

Name  of  Eidge 

Elevation 

1 

Mill  Mountain 

2500  ft. 

\ 

If  they  are  so  narrow,  and  occupy  so  small  a  relative  area,  why  is  it  that  they  have  so  much 
importance,  as  compared  to  plains  regions,  in  the  popular  mind?      


_• What  is  the  average  (ap- 
proximate) elevation  of  the  Folded  Appalachians  as  shown  by  the  contours  on  the  United 

States  map  ?     

With  red  pencil  color  in  (with  parallel  ruled  lines  extending  from  northeast  to  south- 
west) the  province  of  the  Folded  Appalachians.  Fill  in  a  legend  square,  as  indicated  on  the 
diagram  map,  and  mark  it  Folded  Appalachians. 

164 


Study  of 
a  typical 
area  in  the 
Folded 
Appala- 
chians. 


Locate  the  Monterey  (Va.-W.Va.)  sheet  on  your  United  States  map  and  outline  its  area 
in  ink.     Letter  in  the  name  of  the  sheet.     What  is  the  most  pronounced  topographic  feature 


of  the  Monterey  sheet  ? 


What  is  the  general  trend  or  direction  of  the  ridges  ? 


Starting  at  the  southeast  corner,  and  following 

a  diagonal  line  to  the  northwest  corner  of  the  map,  set  down  in  the  table  on  page  309,  and  in 
order,  the  names  of  the  ridges  you  cross  and  the  elevation  of  their  tops. 

In  which  part  of  the  area  are  the  ridges  highest  ? 

Where  are  they  lowest? What  is  the  nature  of  the 

variation  in  elevation  shown  by  the  intervening  ridges  ?  

_.    If  the  valleys  were  all  filled  up  to 

the  level  of  their  bounding  ridges,  what  would  be  the  topography  and  slope  of  the  country  ? 


WThat  is  a  peneplain  ?    (Text-book,  p.  102.) 


Develop-  Just  before  the  last  great  mountain  uplift  (in  Tertiary  time)  the  province  of  the  Folded  Appalachians 

ment  of  was  probably  a  plain,  having  a  general  slope  from  northwest  to  southeast.     Although  the  surface  of  the  plain 

the  present  was  comparatively  smooth,  the  rock  structure  beneath  the  surface  was  made  up  of  great  folds  of  rocks  varying 

topography  very  mucli  in  the  degree  of  their  resistance  to  weathering  and  denudation. 


of  the 
Folded 
Appala- 
chians. 


Make  a  cross  section  along  a  line  between  the  towns  Clover  Creek  and  Mill  Gap.     Let  one  section  of  the 
cross-section  paper  equal  100  feet  in  the  vertical  scale.     What  would  be  the  direction  of  flow  of  the  principal 

streams  on  a  plain  sloping  as  stated  above  ? Would  this 

direction  of  flow  be  parallel  to  or  across  hidden  folds?  . 

Would  the  valleys  of  such  streams  be  widened  most  rapidly  where  the  folds  had  brought  hard  rocks  near  the 

surface,  or  where  they  had  brought  up  soft  rocks  ? 

Which  tributary  valleys  would  be  cut  most  rapidly,  those 

flowing  along  the  hard  surfaces  or  the  soft  ? What  kind  of 

rocks  (hard  or  soft)  do  the  present  ridges  mark  ? Why  are 

the  valleys  between  ridges  so  wide  as  compared  to  the  ridges  themselves  ? 

Name  several  places  where  the 

streams  have  cut  across  the  ridges. . 

Why  are  their  valleys  so  narrow  at  these  points  ?  

What  is  a  water  gap?     (Text-book,  p.  103.)     

165 


Why  are  the  main  streams  now  flowing  southwestward,  between  the  ridges,  instead  of  flowing  to  the  south- 
east in  accordance  with  the  former  slope  of  the  plain  ?  


Human  What  are  the  main  lines  of  travel  in  this  region,  as  indicated  by  the  direction  of  the  roads 

occupation. 

and  the  location  of  the  towns  ?   

Where  do  roads  cross  the  ridges  ?    

What  reasons  can  you 

suggest  for  the  general  absence  of  railroads  ? '. 


Examine  the  Delaware  Water  Gap  sheet. 

Where  do  the  railroads  cross  the  Kittatinny  Range  ?    

Why  is  this  water  gap  more  important 

as  a  transportation  route  than  those  on  the  Monterey  sheet  ?     : 


■ Examine  your  United  States 

contour   map.       What    other    large    streams   have   cut   across   the   Folded    Appalachians  ? 

166 


Why  have  these  large  water  gaps  been  so  important  in  the  history  and  development  of  the 
United  States  ? 


167 


Materials. 


XXXIX.  — THE   CRYSTALLINE  APPALACHIANS 

For  Each  Student.  —  The  contour  map  of  the  United  States.     The  Mt.  Mitchell  (N.  C.-Tenn.) 
sheet,  the  Monterey  ( Va.-W.  Va. )  sheet.       Colored  pencils. 

Purpose  To  study  the  topography  and  settlement  of  a  mountain  region  of  crystalline  rocks  in  a  mature 

stage  of  dissection. 


Introduc- 
tory. 


Location 
and  extent 
of  the 
province  of 
the  Crystal- 
line Appa- 
lachians. 


The  Crystalline  Appalachians  lie  to  the  east  of  the  Folded  Appalachians,  and  include 
the  highest  peaks  of  the  Appalachian  system.  They  were  lofty  mountains  before  the  Folded 
Appalachians  were  formed,  and  had  been  so  long  subjected  to  denudation  that  they  were  worn 
to  a  condition  of  low  relief.  Then,  in  the  uplift  which  elevated  the  region  of  the  folded  Ap- 
palachians, these  crystalline  mountains  were  also  reelevated,  and  it  is  to  this  later  uplift  that 
they  owe  their  present  height.     (Text-book,  pp.  298  and  308.) 

On  your  contour  map  of  the  United  States  plot  the  outline  of  the  province  of  the  Crystalline 
Appalachians  as  shown  on  the  diagram  map.  What  important  section  of  the  country  is  al- 
most wholly  included  within  the  province  of  the  Crystalline  Appalachians  ? 

What  notable  irregularities  in  the  width  of  this  province  are 

apparent? 1 


In  what  sections  of  the  province  are  the  greatest  elevations  ? 

Which  section  has  the  lowest 

altitudes? How  does  the  amount  of  elevation 

affect  the  density  of  settlement  as  indicated  by  the  cities? 


Study  of  an 
area  in  the 

^Crystalline 
Appalachi- 
ans. 


Color  in,  with  red  pencil  (using  crosses  as  indicated  on  the  legend  square  of  the  diagram 
map),  the  province  of  the  Crystalline  Appalachians.  Fill  in  the  proper  legend  square  and 
mark  it  Crystalline  Appalachians. 

The  Mt.  Mitchell,  (1ST.  C.-Tenn.)  sheet  is  chosen  to  illustrate  the  topography  of  the  Crys- 
talline Appalachians.  Locate  the  position  of  this  sheet  on  your  contour  map  of  the  United 
States  and  outline  its  area  with  ink.     Letter  in  the  name  of  the  sheet. 


169 


What  pronounced  difference  in  the  distribution  and  character  of  summit  areas  is  apparent 
on  comparing  the  Mt.  Mitchell  and  the  Monterey  sheets? 


• 


What  is  the  highest  elevation  shown  on  the  Mt.  Mitchell  sheet? 

What  is  the  elevation  of  the  lowest  peaks  ? 

Is  there  any  regularity  in  the 

distribution  of  peaks  of  a  certain  elevation? What  reasons  can  you  suggest  to 

account  for  this? 


How  does  the  size  of  the  streams  shown  on  this  sheet  compare  with  those  on  the  Monterey 
sheet? 


Why  should  the  Mt.  Mitchell  region  be  a  divide  area  ?. 


Make  a  cross  section  along  a  line  (N.  W.  and  S.  E.)  between  Laurel  Knob  and  Big  Tom 
Wilson's,  crossing  Mt.  Mitchell.  Let  one  section  of  the  cross-section  paper  equal  100  feet 
in  the  vertical  scale.     Compare  this  cross  section  with  the  one  from  the  Monterey  sheet. 

What  difference  in  the  width  of  the  valleys  and  ridges  is  shown? 


170 


^^    Human  How  do  the  courses  of  the  roads  in  this  region  compare  with  those  shown  on  the  Mon- 

occupation. 

terey  sheet?    ___. 


Why  have  the  roads  on  the  Mt.  Mitchell  sheet  so  many  short,  sharp  turns?     

How  does  the 

topography  influence  the  course  of  the  railroad?     


Why  has  this  region  extensive  forests?     

As  indicated  by  some  of  the  place  names  on  the  map, 

what  kinds  of  timber  grow  here  ?     


What  is  the  most  important  town  on  the  Mt.  Mitchell  sheet? 

In  a  general  way  (as  1000,  2000,  etc.)  estimate  the  number  of  its  inhabitants. 

Why  are  there  no  more  important  towns  in  the  area?     


Suggest  a  reason  why  the  New  England  section  of  the  Crystalline  Appalachians  has  more  im- 
portant towns.     


171 


Materials. 


XL.  — THE  APPALACHIAN  PIEDMONT  AREA 

For  Each  Student.  —  The  contour  map  of  the  United  States.     The  Farmville  (Va.)  sheet, 
the  Mt.  Mitchell  (N.C.-Tenn.)  sheet.     Colored  pencils. 

p  To  study  the  topography  of  a  very  old  mountain  region,  and  its  adaptation  to  settlement 

and  agriculture. 


Introduc- 
tory. 


Location 
and  extent 
of  the 
Piedmont 
Area. 


The  rocks  underlying  the  Piedmont  Area  are  crystalline,  and  are  complexly  folded  and 
faulted.  They  vary  greatly  in  structure  and  hardness ;  but  the  region  has  been  so  long  de- 
nuded that  its  summits  have  all  been  worn  down  to  a  low  relief,  and  its  drainage  system  is 
perfectly  developed.  More  recently  there  has*  been  a  slight  elevation  of  the  region,  reju- 
venating the  streams.  Over  the  hard  crystalline  rock  lies  a  thick  mantle  of  residual  soil, 
giving  opportunity  for  agricultural  development.  The  region  is  one  which  was  occupied  and 
settled  very  early  in  the  history  of  the  country.     (Text-book,  p.  307.) 

On  your  contour  map  of  the  United  States  plot  the  outline  of  the  Piedmont  Area  as  shown 
on  the  diagram  map.     Why  is  the  Piedmont  Area  most  important  in  the  Southern  States  ? 


What  province  does  it  adjoin  on  the  east?  

What   line    separates   the   two  provinces?     

What  important  crop  is   raised   on  both   the  Piedmont   and  the  Coastal  Plain  provinces  ? 

By  (approximately)  how  much  do  these  two  provinces  differ  in  general 

elevation?    

What  similarity  of  topography  have  they?      

__.  What  is  the  rock  structure  which  underlies  each  ? 


Color  in  lightly  and  uniformly,  using  red  pencil,  the  area  of  the  Piedmont  Province  as  you 
have  outlined  it  on  your  United  States  map.  Fill  in  the  proper  legend  square  •  and  mark  it 
Appalachian  Piedmont. 


173 


Study  of  a  Locate  the  position  of  the  Farmville  (Va.)  sheet  on  your  United  States  map  and  outline 

typical  sec-  its  area  with  ink.     Letter  in  the  name  of  the  sheet. 

tion  of  the  What  is  the  nature  of  the  topography  shown  on  the  Farmville  sheet  ? 

Piedmont  r         r  J 

Area. 


What  regi on 

previously  studied  does  it  most  resemble?     

How   do   you    account    for    this    similarity? 

Why  should  this  region,  which   is   so   like   a   plain,  be   called   an   old   mountain   region  ? 


The  topography  of  the  Farmville  sheet  was  once  as  rugged  as  that  of  the  Mt.  Mitchell  sheet. 
What  can  you  say  regarding  the  amount  of  time  which  must  have  elapsed  since  it  had  such  a 

topography  ?    


State  why  the  Piedmont  Area  is  called  a  peneplain. 


What  is  a  monadnock  ?  (Text-book,  p.  298.) 


What  example  of  a  monadnock  do  you  find  on  the  Farmville  sheet? 

How  many  feet  does  the  Appomattox  River  descend  within  the  area 

of  the  map  ?     .Why  has  it  such  a  meandering  course  ? 


174 


• 


: Why  are  the 

small  tributary  streams  eroding  their  valleys  ?     

Human  What  is  the  pattern  of  the  roads  in  this  region? 

occupation. 


Does  it  coincide  with  that  of  the  drainage  lines  ?     Does  it  coincide  with  the 

divides?      _._      Why?     


• 


What    indication    do    the 

number,  size,  and  location  of  the  towns  (individual  houses  are  not  shown  on  this  sheet)  and 

the  number  of  the  railroads  give  that  this  is  a  rich  agricultural  region? 


Write  a  short  paragraph  describing  the  nature  of  the  country,  with  respect  to  topography, 
agriculture,  and  drainage  conditions,  that  you  would  see  looking  from  an  elevated  point,  like 
Willis  Mountain. 


175 


t 


Materials.  For  Each  Student. 

Colored  pencils. 


XLL— THE   LAURENTIAN    HIGHLANDS 


The  contour  map  of  the  United  States.     The  Lake  Placid  (N.Y.)  sheet. 


Purpose.  To  study  the  topography  of  the  old  crystalline  mountam  areas  known  as  the  Laurentian  High- 

lands; and  the  utilization  of  the  Adirondack  portion  of  these  as  a  vacation  and  resort  country. 


Introduc- 
tory. 


Location 
and  extent 
of  the 
Laurentian 
Highlands. 


To  the  north  of  the  eastern  part  of  the  United  States  is  found  a  great  area  of  crystalline 
rock,  known  as  the  Laurentian  Highlands,  which  is  considered  to  be  made  up  of  some  of  the 
oldest  rocks  of  the  earth's  crust.  The  Lake  Superior  Highlands  and  the  Adirondack  Mountains 
are  outlying  masses  of  these  Laurentian  Highlands,  which  at  these  points  project  into  the 
territory  of  the  United  States.     (Text-book,  pp.  107  and  302.) 

Outline,  on  your  contour  map  of  the  United  States,  the  areas  of  the  Laurentian  Highlands, 
as  shown  on  the  diagram  map. 

What  is  the  relative  importance  of  the  Laurentian  Highlands  in  the  United  States  with 

respect  to  the  amount  of  territory  they  comprise  ?     


Why  does  their  location  further  lessen  their  im- 


portance ? 


What  well-known  city  is  situated  in  the  Lake  Superior  Highland  region  ? 
To  what  conditions  does  this  city  owe  its  importance?     


Why  was  Lake  Champlain,  in  the 

eastern  part  of  the  Adirondacks,  so  important  in  the  early  history  of  the  United  States  ? 


On  your  United  States  map  color  in  with  red  pencil  (using  circles  as  indicated  on  the 
legend  square  of  the  diagram  map)  the  areas  of  the  Laurentian  Highlands  in  the  United  States 
as  you  have  outlined  them.     Fill  in  the  proper  legend  square. 


177 


Study  of  a  Locate  the  position  of  the  Lake  Placid  (N.Y.)  sheet  on  your  United  States  map,  and  out- 

section  of      jjne  jts  area  with  ink.     Letter  in  the  name  of  the  sheet.     What  is  the  shape  and  arrangement 


the  Adiron 
dacks. 


of  the  mountain  masses  shown  on  this  sheet  ? 


How  do  they  differ  in  shape  from  the  Folded 

Appalachians  ? 


From  the  Crystalline  Appalachians?    

Which  is  the  highest  mountain 

shown  on  this  sheet,  and  what  is  its  elevation?   

What  is  the  elevation  of  several  other  important  peaks? 

What  do  the  contour  lines  show  as 

to  the  nature  of  the  outline  of  the  -mountains,  —  are  they  sharp  and  rugged  or  smooth  and 

flowing?    What  does  this  condition  indicate 

as  to  the  age  of  the  mountains  ? 

What  is  the  evidence  on  this  point  of  the  number  and 

shape  of  the  valleys  on  the  mountain  slopes?     


How  may  differences  in  rock  account  for  the 

wide  valleys  between  the  mountains  ?     


What  is  the  elevation  of  the  mountains  as 

compared  to  the  approximate  general  elevation  of  the  wide  valleys  between  them? 


178 


- Do  the 

mountains  appear  high  or  low  ?  How  do  you 

explain    the    presence    of    so    many    lakes    and    swamps    in   a   mature   mountain   region  ? 


If  the  swamps  were  formerly  lakes,  what  must  have  happened  to  them  since  ? 


Human  What  do  you  observe  as  to  the  density  and  distribution  of  the  settlement  of  this  region  ? 

occupation. 


Why  are  the  roads  so  comparatively  numerous  in  this  mountain  region  ? 


• 


Near   what   great 

centers  of  population  are  the  Adirondack  Mountains  ?     


What  is  the  bearing  of  this  fact  on 

its  development  as  a  resort  region? 


What  is  the  attraction  of  the  mountains  for  city  people  ? 


What  recreation  and  sport  do  the  lakes  and  rivers  afford? 

179 


Why  is  there  an  especially  large 

settlement  around  Mirror  Lake  and  Lake  Placid  ? 


Write  a  short  paragraph  summarizing  the  attractions  of  the  Adirondack  Mountains  as  a 
resort  country. 


180 


Materials. 


Purpose. 


Introduc- 
tory. 


Location 
and  extent 
of  the 
Rocky 
Mountain 
province. 


XLIL  — THE   ROCKY  MOUNTAINS 

For  Each  Student.  —  The  contour  map  of  the  United  States.  The  Saw  Tooth  (Idaho)  sheet.  Colored 
pencils. 

For  General  Class  Use.  — A  wall  map  of  the  United  States  showing  railroads. 

To  gain  an  appreciation  of  the  topographic  features  of  the  Rocky  Mountains,  and  of  the  man- 
ner in  which  the  presence  of  ores  and  open  valleys  in  the  mountains  has  affected  their  settlement. 

The  Rocky  Mountains  constitute  the  most  easterly  member  of  the  Western  Cordillera,  a 
general  term  given  to  all  the  mountainous  section  of  the  United  States  which  lies,  for  the  most 
part,  west  of  the  105th  meridian.  Because  of  its  physiography,  the  Western  Cordillera,  as  a 
whole,  is  a  sparsely  settled  region ;  but  local  conditions,  in  places,  attract  a  comparatively 
large  population.     (Text-book,  pp.  106-107,  and  314-315.) 

On  your  United  States  map  outline  the  area  of  the  Rocky  Mountain  province  as  shown  on 
the  diagram  map. 

What  is  the  north-south  length  of  the  Rockies?     


How  do  they  compare  in  this  respect  to  the  Appalachians? 


What   other    factors 


make  the  Rockies  a  more  complete  barrier  to  travel  than  the  Appalachians  ? 


By  consult- 
ing the  wall  map  of  the  United  States,  locate  and  plot  on  your  United  States  map  the  route 
followed  by  the  transcontinental  railroads  in  crossing  the  Rockies.  As  shown  by  the  topog- 
raphy on  your   United   States  map,  what   factors  determine   the  location  of   these  routes? 


How  has  the  presence  of  the  railroads  affected  settlement  in  the  Rockies  ? 


What  impor- 


181 


tant  cities  are  located  on  these  routes  ? 


Color  in,  with  red  pencil  (using  the  angle  symbol 

shown  in  the  legend  square),  the  province  of  the  Rocky  Mountains  as  you  have  outlined  it  on 

your  map.     Fill  in  the  proper  legend  square  and  mark  it  Rocky  Mountains. 

Study  of  Locate  the  position  of  the  Saw-Tooth  (Idaho)  sheet  on  your  map  of  the  United  States, 

an  area  in     anci  outline  its  area  with  ink.     Letter  in  the  name  of  the  sheet, 
the  Rocky 

Mountains.  What  is  the  approximate  general  elevation  of  this  area?     


What  are  the  elevations  of  some  of  the  higher  peaks! 


What  are  the  ele- 
vations of  the  bottoms  of  the  larger  valleys?     

As  indicated  by  these  conditions,  do  the  indi- 
vidual ranges  and  peaks  constitute  the  mountain  uplift,  or  does  the  region  as  a  whole  ?     

By  what  processes  are  the  lesser  ranges  and  peaks 

developed  ?     


Does  the  topography  of  this  region  indicate  young,  mature,  or  old  conditions? 

Describe  the  topography  of  the  country  as  it 

would  appear  to  an  observer  stationed  on  the  summit  of  Big  Peak.      


182 


What  evidence  indicative  of  former  glaciation  of  this  region  do  you  note?     

.+ In  what  por- 
tion of  the  map  are  lakes  especially  conspicuous?     

Where  else  do  very  small  lakes  occur?     

What  is  the  significance  of  the  occurrence  and  location  of  these  smaller  lakes?     


How    might 

deposits  from  glacial  streams  account  for  the  wide,  level-floored  valley  in  the  northern  part  of 


this  area? 


Human  Locate  the  one  road  of  the  area  which  continues  unbroken  across  one  of  the  mountains. 

occupation. 

How  many  feet  must  one  climb  between  Galena  and  the  summit  of  the  divide?     

In  how  many  miles?     Why  has  the  road  in  this  section 

several  very  sharp  turns?     

What  two  sections  of  the  area  have  invited  settlement?     


What  was  the  reason  for  the 

settlement  in  each  case? 


183 


Suggest  a  reason  why  the  mines  in  the  southeast  section  are  closely 
grouped.     


What  is  the  probable  method  of  transportation  between  the  Silver  Star  mine  and 
the  King  of  the  West  mine?     

About  how  many  square  miles  of  land  are  available  for  agriculture  in  the  large  valley  to 

the  north?     What  is  the  nature  and  importance  of  Rocky  Mountain 

Parks?     (See  Text-book,  p.  95.)     


Write  a  short  paragraph  summarizing  the  significance  of  the  Rocky  Mountains  as  a  bar- 
rier to  transportation  and  travel,  and  the  reasons  for  their  settlement  in  isolated  areas. 


184 


Materials. 
Purpose. 

Introduc- 
tory. 


Location  of 
the  area. 


XLIII.  —  MOUNTAIN   GLACIERS   AND   THE  CONTINENTAL  DIVIDE 

For  Each  Student.  —  Contour  map  of  the  United  States.     Chief  Mountain  (Mont.)  sheet. 

To  study  the  topography  of  a  mountain  region  having  existing  glaciers,  and  the  evidence  it 
presents  of  former  more  extensive  glaciation. 

The  mountain  region  shown  in  this  sheet  has  topographic  characteristics  of  a  stage 
between  youth  and  maturity.  The  normal  topography  of  weathering  and  stream  erosion  has, 
however,  been  modified  very  much  by  glacial  erosion.  The  glaciers  which  exist  to-day  are 
but  remnants  of  former  much  greater  ones,  as  is  indicated  by  the  topography.  The  region  has 
a  further  interest  in  that  it  is  along  the  line  of  the  Continental  Divide.  This  map,  and  those 
used  in  the  exercises  on  the  Colorado  Plateau  and  Canyon,  and  the  Yosemite,  are  commended 
for  their  excellence  of  topographic  expression;  they  illustrate  the  possibilities  of  contour 
maps  in  expressing  land  forms.     (Text-book,  pp.  137-139,  141-142.) 

Locate  the  position  of  the  Chief  Mountain  (Mont.)  sheet  on  your  contour  map  of  the  United 
States,  and  outline  the  area  with  ink.     Letter  in  the  name  of  the  sheet. 

In  what  physiographic  province  is  the  Chief  Mountain  region?  

What  is  the  latitude  of  the  northern  edge  of  the  sheet?     


What  boundary  line  does  it  mark?     

Continental  Examine   the   Chief   Mountain   sheet.     What   determines   the  line  of   the   Continental 

Divide. 

Divide?     '_ 

What  is  the  eventual  destination  of  the  precipitation  that  falls  on  the  eastern  side  of  the 

divide?     u 

On  the  western  side?     

What  is  the  effect  of  the  presence  of  forests  on  the  rate  of  the  run  off  of  rain  and  snow  water 
from  a  land  surface?     


Why  has  this  area  been  made  a  "  Forest  Beserve"  ? 


185 


Why  is  the  pres- 
ence of  forests  desirable  at  the  headwaters  of  streams  ?     


Existing  Name  the  larger  glaciers  mapped  in  this  area, 

glaciers. 


What     is     their    general    distribution? 


On  which  side  of  the  divide  are  the  greater  number  ?  

What  explanation  can  you  offer  to  account  for  this  fact  ? 


Which  glacier  is  largest?      

What  is  its  length  in  miles  and  fractions  of  a  mile  ?     

Its  width?     How  does  this  compare  with  the 

dimensions  of  Alpine  glaciers?     (See  Text-book,  p.  137.)     


What  is  the  lowest  altitude  to 

which  the  glaciers  descend?     How  many  of  the  glaciers  descend  to 

about  the  7500  foot  level  ?     What  reasons  can  you  suggest  for  this  uni- 
formity in  the  altitude  of  their  melting  ends?     


186 


Evidence  What  provinces  of  the  United  States,  which  you  have  previously  studied,  were  character- 

of  former 


#gfea.teLr.         ized  by  the  presence  of  many  lakes  ? 
glaciation.  '    .      r  J 


What  is  the  significance  of  the  many  lakes  in  this 

region  ? 

Describe  the  shape  of  the  depressions  occupied  by  the  existing  glaciers. 


What  is  a  cirque?     (See  Text-book,  p.  142.)     .. 


Identify  other  cirques  in  this  region  besides  those 
occupied  at  present  by  glaciers.     


Make  a  cross  section  of  the  valley  of  Swiftcurrent  Creek  (emptying  into  the  Sherburne 
Lakes)  on  a  line  (N.W.-S.E.)  between  Point  Mt.  and  Appekunny  Mt.  Let  one  division  of 
the  cross-section  paper  equal  200  feet  in  the  vertical  scale.     What  is  the  shape  of  this  valley 

cross  section?     ■_ 


How  does  it  differ  from  the  shape  of  the  cross  sections  of  valleys  in  the  Appalachian  Plateau? 


What  is  the  significance  of  a  U-shaped  valley  ? 


187 


Locate  and  name  other  valleys  on  this  sheet 

which  have  similarly  shaped  valleys.     


What  are  hanging  valleys  ?  (Text-book,  p.  142.) 


Why  are  waterfalls  present  at  the  mouths  of  hanging  valleys  ? 


Locate  examples  of  hanging 

valleys;  for  example,  in  St.  Mary  River  valley.      


What   is   the  evidence  of  the  presence  of 

lakes,  cirques,  the   U-shape  of  the  valley  cross  sections,  and  hanging  valleys  on  the  question 

of  the  former  greater  extension  of  the  glaciers  ?      


188 


( 


XLIV.  — THE   COLUMBIA   LAVA   PLATEAU 

Materials.  For  Each  Student. — The  contour  map  of  the  United  States.    The  Spokane  (Wash.-Idaho)  sheet. 

The  Denver  (Colo)  sheet.    Colored  pencils. 

Purpose.  To  study  the  topography  and  settlement  of  the  Columbia  Lava  Plateau. 

Introduc-  The  region  of  the  Columbia  Lava  Plateau  is  made  up  of  great  sheets  of  lava,  which,  in  a 

tory.  comparatively  recent  geological  period,  welled  up  from  fissures  in  the  earth's  crust,  and  spread 

over  the  country  as  immense  floods  of  molten  rock.  Since  then  the  plateau  surface  has  been 
much  dissected  by  denudation  ;  and  a  thick  mantle  of  residual  soil  covers  large  portions  of  its 
area.     (Text-book,  pp.  125-126.) 

Location  On  your  contour  map  of  the  United  States  plot  the  area  of  the  Columbia  Lava  Plateau  as 

and  extent 

of  the  area,   outlined  on  the  diagram  map.     What  states  are  partly  included  in  this  province  ?     

i What 

range  of  altitude  do  you  note?     

What  portion  of  the  province  is  most  plateau-like  in  its 

topography?     

•     Why  is  the  portion  of  the  province  which  adjoins  the  course  of  the  Colum- 
bia River  most  dissected  ?      r 


Color  in,  with  brown  pencil  (using  the  symbol  indicated  in  the  legend  square  on  the  dia- 
gram map),  the  province  of  the  Columbia  Lava  Plateau.  Fill  in  the  proper  legend  square  and 
mark  it  Columbia  Lava  Plateau. 

Study  of  a  Locate  the  position  of  the  Spokane  (Wash.-Idaho)  sheet  on  your  map  of  the  United  States, 

section  of      and  outline  its  area  with  ink.     Letter  in  the  name  of  the  sheet. 

the  Colum-  What  physiographic  province  borders  the  Columbia  Lava  Plateau  on  the  east? 

along  its        What  portion  of  the  area  mapped  on  the  Spokane 

eastern  « 

margin.         sheet  is  to  be  included  in  the  Pocky  Mountain  Province  ?     

What  was  the  approximate  general  altitude  of  this  part  of  the  Columbia  Lava 

Plateau  before  dissection,  as  shown  on  this  sheet?     What  are  the 

physiographic  characteristics  of  Five  Mile  Prairie?     

189 


What  physiographic  term  would  you 

apply  to  it?      Locate  other  similar  areas. 

Are   mesas   most   com- 
mon in  a  region  of  little  or  great  rainfall  ? In 

regions  of  horizontal  or  of  inclined  strata?    

What  does  this  indicate  regarding  the  position  of  the  strata  and  the  rainfall  conditions  on  the 

Columbia  Lava  Plateau?     

Account    for   the 

presence  of  so  many  permanent   streams   in  this   section   of  the  Columbia  Lava  Plateau. 


Human  Is  there  more  agricultural  settlement  on  the  level  areas,  such  as  the  mesa  tops,  or  on  the 

occupation. 

valley  slopes?     The  soil   of  the   Columbia 

Lava  Plateau  is  residual, — that  is,  it  is  formed  by  the  decay  of  the  lava  rocks,  and  rests 
directly  on  them.     Why  should  there  be  a  greater  depth  of  this  soil  on  the  uplands  than  on 

the  valley  sides?     1 


What  is  the  significance  of  the  location  of  Spokane  with  reference  to.the  Spokane  Valley 
as  a  highway?     


Eemembering  that  the  Great  Northern  is  a  transcontinental  railroad,  what 
influence  has  the  location  of  Spokane  had  on  the  course  of  railroads  ?     „ 


190 


There  is  a  waterfall 

in  the  Spokane  River  where  its  course  passes  through  Spokane.     What  is  the  bearing  of  this 

fact  on  the  exact  location  and  growth  of  Spokane? 


Write  a  short  paragraph  contrasting  and  comparing  the  sites  and  environs  of  the  cities  of 
Denver  and  Spokane. 


191 


• 


XLV.  — THE  GREAT  BASIN   REGION 

Materials.  For  Each  Student.  —  The   contour   map   of  the  United  States.     The  Granite    Range    (Nev.) 

sheet.    Colored  pencils. 

Purpose.  To  gain  an  appreciation  of  the  physical  geography  of  the  Great  Basin,  Region. 


Introduc- 
tory. 


Location 
and  extent 
of  the  Great 
Basin. 


The  Great  Basin  is  a  region  of  interior  drainage.  (Text-book,  p.  324.)  Its  area  is  encom- 
passed by  more  elevated  mountain  and  plateau  barriers,  and  the  precipitation  of  the  present 
climate  is  not  sufficient  in  amount  to  enable  the  basin  to  fill  up  and  overflow  at  some  point  on 
its  rim.  In  recent  geological  times,  however,  the  climate  of  the  Great  Basin  Region  was 
more  humid,  and  a  large  lake,  Lake  Bonneville  (Text-book,  pp.  163-164)  occupied  a  great 
extent  of  its  area,  the  mountain  ranges  projecting  as  islands  above  its  level. 

A  region  to  the  southeast  marked  "  Open  Basins  "  has  similar  conditions  to  those  of  the 
Great  Basin,  except  that  most  of  the  drainage  escapes  to  the  sea. 

On  your  contour  map  of  the  United  States  plot  the  outline  of  the  area  of  the  Great  Basin 
as  indicated  on  the  diagram  map.     What  state  and  parts  of  states  does  it  include  within  its 

limits? 

What  is  the  general  nature  of  its 


topography  ? 


What  is  the  most  important  stream  within  the  Great  Basin  ? 
Where  is  its  source?       


Its  mouth?     

In  what  respects  are  the  courses  of  the  smaller  streams  similar 

to  that  of  the  Humboldt  River  ? 


What   is   the   general    trend    of   the   mountain   ranges  ? 


Figure  301  of  the  Text-book  is  a  map  of  the  extent  of  the  former  Lake  Bonneville. 
Outline  its  extent,  approximately,  on  your  contour  map  of  the  United  States,  using  a  dotted 
line.     Mark  the  area,  thus  inclosed,  Lake  Bonneville. 


193 


Where  was  the  probable  region  of  outflow  of  former  Lake  Bonneville,  as  indicated  by  the 
contour  lines  on  your  United  States  map  ? 
What  approximate  proportion  of  its  area  does  the 

present  Great  Salt  Lake  occupy  ?     What  does 

the  location  of  Great  Salt  Lake  indicate  as  to  the  deepest  portion  of  the  former  Lake  Bonne- 
ville ?    ' 

Suggest   a  reason  why   the  main  settlement    of   the  Great  Basin  region  centers 
about  the  present  lakes  within  its  area.     


Color  in,  with  yellow  pencil  (using  ruled  lines  as  indicated  in  the  legend  square  of  the 
diagram  map),  the  area  of  the  Great  Basin  region  as  you  have  outlined  it  on  your  United 
States  map.     Fill  in  the  proper  legend  square  and  mark  it  Great  Basin. 

Studv  of  a  Locate  the  position  of  the  Granite  Range  (Nev.)  sheet  on  your  map  of  the  United  States 

typical  area   and  outline  its  area  in  ink.     Letter  in  the  name  of  the  sheet. 

within  the  What  three  prominent  features  make  up  the  physiography  of  this  area  ?      

Great 

Basin. 

What  is   the 

general    trend    of    the    mountain    ranges?      

The  Selenite  Range  is  typical  of   many  of  the   Basin  Ranges.     What  is   the  approximate 

length  of  the  Selenite  Range  ?     Its  elevation  ?      

How  do  these  dimensions  and  its  isolation  compare  with  ranges  of  the  Rocky  Mountain  region  ? 


Where  are  the  sources  of  the  small  streams?     

Why  do  they  disappear  when  they  reach 
the  level  places?     


What  becomes  of  the  dissolved  material  they  are  carrying  ?     (Text-book, 

pp.  87  and  169.)      . 

191 


• 


Where  are  such  deposits  being  formed  in  this  area  ? 


What    becomes   of   the 
sediment  they  carry?     

What  suggestion  does  this  give  as  to  thexn-igin  of  the  fiats  between  the 
mountain  ranges  ?     


What  would  be  the  bearing  of  the  former  greater  extent  of  Pyramid 

Lake  on  the  question  of  the  origin  of  these  flats  ?     


Human  Why  are  there  no  cities  within  this  area  ? 

occupation. 


* What  one  industry  is  indicated  by  a  place 

name?     Why  should  salt  be  found  in  such 

a  situation?    (Text-book,  p.  163.) 


195 


• 


XLVL—  THE  COLORADO  CANYON  AND  PLATEAU 

Materials.  For  Each  Student.  —  Contour  map  of  the  United  States.     The  Bright  Angel  (Ariz.)  sheet.    Col- 

ored pencils. 

Purpose.  To  study  the  erosional  ivork  of  a  great  river,  cutting  through  thick  horizontal  strata  in  an 

arid  plateau  region. 


Introduc- 
tory. 


Location 
and  extent 
of  the 
province. 


The  Colorado  Kiver  has  its  source  among,  and  is  fed  by,  the  melting  snows  of  the  moun- 
tains of  the  lofty  central  Rocky  Mountains,  being  formed  by  the  junction  of  the  Green  and  the 
Grand  rivers.  The  river  waters  are  abundantly  supplied  with  sediment  by  the  weathering  of 
the  mountain  slopes,  yet  are  not  overloaded.  Consequently,  in  flowing  across  the  plateau  to 
the  south  and  west,  the  river  has  been  able,  by  means  of  its  rock  tools,  to  carve  the  remark- 
able canyon  which  bears  its  name.  The  Colorado  Plateau  Province  itself  consists  of  a  series 
of  rock  platforms,  level  in  topography  and  separated  one  from  the  other  by  fault  and  weather- 
ing escarpments.     (Text-book,  pp.  81-82  and  322-323.) 

On  your  contour  map  of  the  United  States  plot  the  outline  of  the  area  of  the  Colorado 
Plateau  as  shown  on  the  diagram  map. 

What  states  lie  partly  in  this  province  ? 


Colorado  Plateau,  excluding  the  Canyon  ? 


What  is  its  approximate  elevation  ? 

What  is  the  nature  of  the  topography  of  the 


Approximately  how  many  feet  does  the  Colorado  River  descend  between  the  point  of  junction 
of  the   Green   and   Grand  rivers  and   the  point  where  it   first  touches  the  Nevada   state 

boundary  line  ?     About  how  long  is  this  portion  of  its  course  ? 

\ How  does  its  average  descent  per  mile  compare  with  that  of  the 

Mississippi  below  Cairo?     (See  exercise  on  Mississippi  Flood-plain   and  Delta  Province.) 


Why  has  the  Colorado  River  such  great  erosive  power  ? . 


197 


On  your  contour  map  of  the  United  States  color  in  with  green  pencil  (using  the  symbol 

shown  in  the  legend  square)  the  area  of  the  Colorado  Plateau.     Fill  in  the  proper  legend 

square  and  mark  it  Colorado  Plateau. 

Study  of  Locate  the  position  of  the  Bright  Angel  sheet  and  plot  the  outline  of  its  area  on  your 

the  Grand      United  States  map.     Letter  in  the  name  of  the  sheet.     What  is  the  general  direction  of  slope 

Canyon  and  Q£  ^e  Colorado  Plateau  as  shown  by  the  areas  named  the  Kaibab  Plateau  to  the  north  of  the 
adjacent 

areas  Canyon,  and  the  Coconino  Plateau  to  the  south?     

. What  effect  has  this  had  on  the  course  of 

small  streams  on  the  plateau  surface?    : 

How  may  these  conditions  account  for  the  longer  slope  of  the  north  side  of  the  Grand  Canyon 
at  this  point  ?     


What  is  the  scale  of  the  Bright  Angel  sheet? 

What  is  the  approximate  width  of  the  Grand  Canyon  on  a  line  directly  north  from  Grand 

Canyon  station?     What  is  the  greatest  depth  of  the  canyon 

shown?     How  does  this  width  and  depth  compare  with  the  dimen- 
sions of  the  Niagara  Gorge?     


What  condition  of  slope  is  indicated  where  the  contour  lines  are  run  together  to  form  a 

ribbon  of  solid  brown?     ___•_ 1 

What  kind  of  rock  layers,  hard  or  soft,  would  be  marked  by  vertical 

cliffs?      L Account  for  the  isolated  monu- 
ments, like  the  Isis  Temple,  left  standing  as  outliers  of  the  canyon  wall. 


198 


Name  various  illustrations  of  stages  in  the  process  of  formation  of  such  buttes  and  mesas. 


In  what  kind  of  rock  is  the  river  cutting  at  present,  as  indicated  by  the  name  of  the 

inner  gorge  ?     Why  is  there  no  alternation 

of  vertical  cliffs  and  gentler  talus  slopes  in  this  inner  gorge?     

What  is  the  nature  of  the  river's  flow  here,  as  shown  by  the  conventional 

sign  ? 


Human  How  many  houses  are  mapped  on  this  area  ?      What  two 

occupation. 

factors  account  for  this  very  sparse  settlement?     


Why  is  a  railroad  built  to  the  Grand  Canyon  ? 


Why  is  this  canyon  an  even  greater  barrier  to  travel  than  a  high  mountain  range  ? 


Write  a  short  paragraph  telling  what  you  would  expect  to  see  if  you  were  standing  at 
Yavapai  Point  and  looking  out  over,  and  down  into,  the  Grand  Canyon. 


199 


# 


Materials. 


Purpose. 


Introduc- 
tory. 


Location 
of  the 
Yosemite 
Valley. 


XLVII.  —  THE   YOSEMITE   VALLEY 

For  Each  Student.  —  The  contour  map  of  the  United  States.  The  Yosemite  (Cal.)  quadrangle. 
Map  of  the  Yosemite  Valley,  California. 

To  gain  an  appreciation  of  the  setting,  scenic  magnificence,  and  topographic  relations  of  the 
Yosemite  Valley. 

The  four  preeminent  scenic  resources  of  the  United  States  are  Niagara  Falls,  the  Grand 
Canyon  of  the  Colorado,  the  Yellowstone  National  Park,  and  the  Yosemite  Valley.  Three  of 
these,  and  the  fourth  in  part,  owe  their  origin  and  interest  to  the  results  of  the  erosive  work  of 
water,  active  either  as  a  running  stream  or  in  the  form  of  glacial  ice.  The  features  of  the 
Yosemite  Valley  are  the  resultant  of  both  ice  and  water  work  on  a  jointed,  granite  rock.  During 
the  Glacial  Period  huge  glaciers  radiated  from  the  higher  summits  of  the  Yosemite  region, 
and,  moving  downward  toward  the  lowlands,  scoured  out  and  differentially  eroded  their  valley 
channels,  leaving  the  smaller  valleys  hanging  at  their  mouths,  far  above  the  floor  of  the  main 
valleys.  As  a  result  of  this  differential  glacial  erosion,  waterfalls  were  born  when  the  valleys 
were  eventually  freed  of  ice,  so  that  the  streams  could  again  flow. 

Locate  the  position  of  the  Yosemite  sheet  on  your  contour  map  of  the  United  States,  and 
outline  its  area  with  ink.     Letter  in  the  name  of  the  sheet. 

As  indicated  by  the  contours  on  the  United  States  map,  why  is  the  Yosemite  Valley  said 

to  be  in  the  "  High  Sierras"?     


Topo- 
graphic 
relations. 


What  is  the  approximate  general  elevation  above  sea  level  of 

the  summits  in  the  Yosemite  region  as  shown  on  the  Yosemite  quadrangle  ?     

Of  the  valley  bottoms?     Explain  the  absence  of  railroads 

in  this  region. 

In  what  respect  does  the  Yosemite  Valley  differ  markedly  from  other  valleys  in  the  region  ? 


What  other  valley  has  similar  features  on  a  lesser  scale  ? 


What  distinct  difference  in  the  valley  form  of  the  Hetch  Hetchy  Valley  and 

the   Grand   Canyon    of    the    Tuolumne    (both    of    the    Tuolumne    River)    do  you   note  ? 


201 


Which  of  these  forms  is  most  characteristic  of  glacial  erosion?     -. 

Is  the  form  of  the  Yosemite  Valley  typical  of  glacial  or  stream  erosion  ? 

Examine  the  map  of  Yosemite  Valley.     What  particularly  striking  topographic  forms  are 
indicated  by  the  many  areas  of  crowded  contour  lines? 

How  high  is  the  cliff   of   El   Capitan?     Describe  the 

Half  Dome  as  to  height  above  base,  shape,  and  steepness  of  sides.     


What  are  joint  planes? 

(Text-book,  p.  38.) 


How  would  the  presence  of  such  joint  planes  in  massive  granite  rock 

aid  in  the  development  of  precipices?     


How  would  such  jointing  in  the  rock  affect  the  erosive  action  of  a  glacier  moving  down 
the  valley  of  the  Merced  River?     


What  evidence  of  such  action  is  apparent  on  the  map  ? 
202 


" 


( 


Why  would  a  large  valley  glacier  erode  deeper  than  a  small  one  ? 


Since  there  were  glaciers 

in  the  valleys  of  both  the  Merced  River  and  the  Yoseinite  Creek,  why  is  the  valley  floor  of 

the  latter  now  so  high  above  that  of  the  Merced  River?     


, What  is  the  height  of  the  upper 

Yosemite  Falls?     . In  what  way  have  weathering  and  erosion  since 

the  Glacial  period  combined  to  give  the  Merced  River  a  flat  valley  floor?     


What  has  been 

the  effect  of  this  on  the  course  of  the  river?     


Why  has  this  region  been  made   a   National 

Park?         :_ 


203 


Write  a  short  paragraph  telling  what  scenic  and  physiographic  phenomena  you  would 
anticipate  seeing  on  a  visit  to  the  Yosemite  Valley. 


< 

204 


XL VIII.— MT.    SHASTA  AND  SURROUNDING  REGION 

Materials.  For  Each  Student.  —  The  contour  map  of  the  United  States.      The  Shasta  (Cal.)  and  the 

Shasta  Special  sheets. 

Purpose.  To  study  a  volcanic  cone  and  a  region  of  former  volcanic  activity. 

Introduc-  Mount  Shasta  is  the  cone  of  a  volcano  which  has  been  dormant  or  extinct  for  many  centuries. 

tory.  In  the  region  adjoining  Mt.  Shasta  there  is  other  evidence  of  former  volcanic  activity.     Since 

the  cessation  of  eruptions  from  Mt.  Shasta,  erosion  and  weathering  have  to  some  extent  modi- 
fied the  original  outline  and  contour  of  the  cone.     (Text-book,  p.  121.) 

Location  of  Locate  the  position  of  the  Shasta  (Cal.)  sheet,  and  outline  its  area  with  ink  on  your 

Mt.  Shasta.  United  States  map.  Letter  in  the  name  of  the  sheet.  Mark  the  position  of  Mt.  Shasta  with 
a  cross  (x). 

Mt.  Shasta  Examine  the  Shasta  (Cal.)  sheet.     What  is  the  difference  in  outline  and  topography 

and  the 

adjoining      between  Mt.  Shasta  and  the  adjacent  mountain  regions?    

region. 


What  is  the  altitude  of 

Mt.  Shasta?     How  does  this  elevation  compare  with  that  of  the 

highest  points  in  the  surrounding  region?     

Why  is  Mt.  Shasta  a  dominating  feature  of 

the  landscape  in  Northern  California?     


Assume  the  floor  of  the  valley  from  which  Mt.  Shasta  rises  to  represent  the  original  level  of 
the  country,  and  on  this  basis  calculate  the  approximate  number  of  cubic  miles  of  volcanic 

material  which  has  been  ejected  to  build  up  the  cone.       


Shastina,  a  minor  summit  to  the  west  of  the  main  Mt.  Shasta  summit,  is  a  secondary 
cone.     What  other  near-by  mountains  are  of  volcanic  origin,  as  suggested  by  their  form  or  the 

names  given  them  ?     

205 


Topog-  Make  a  cross  section  of  Mt.  Shasta  on  a  line  passing  through  Butteville  and  Shastina,  and 

If^Sluu  t      extending  to  the  eastern  edge  of  the  map.     Let  one  division  of  the  cross-section  paper  equal 
600  feet  in  the  vertical  scale.     This  will  give  a  vertical  exaggeration  of  about  four  times. 

What  is  the  general  shape  of  a  volcanic  cone  as  shown  by  this  cross  section  ?     , 


Are  its  slopes,  in  general,  steep  or  gentle  as  compared  to  other  mountains? 
Explain  why  they  are  so  much  steeper  near 

the  summit. 

In  what  way  does   the  cross  section   of   Shastina   suggest  that   it   is   a   secondary  cone? 


Topo-  Examine  the  Shasta  Special  sheet.      In   what  two  respects  does   Mt.    Shasta  depart 

graphic 

details  of       from  f    t  ? 

Mt.Shasta.  y  


Suggest  a  reason  why  the  shape  of  the  lava  flows  very  much 

resembles  that  of  the  glaciers.    


On  which  side  of  the  cone  are  valleys  developed  most 

markedly?     What  is  the  general  pattern  of  the  drainage? 

Suggest  a  reason  for  the  origin  of  the  buttes 

on  the  south  side  of  the  cone. 


206 


What  do  the  place-names  Cinder  and  Ash  suggest  as  to  the 

material  where  they  occur?     


Why  should  the  larger  glaciers  be  on  the  north  side  of  the  cone  ? 


Write  a  short  paragraph  summarizing  the  topographic  characteristics  of  a  volcanic  cone 
composed  partly  of  ash  and  partly  of  lava. 


207 


Materials. 


Purpose. 


Introduc- 
tory. 


Location 
and  extent 
of  these 
regions. 


XLIX.  —  PIEDMONT   VALLEYS   OF   THE   PACIFIC   SLOPE 

For  Each  Student. — The  contour  map  of  the  United  States.  The  Cucamonga  (Cal.)  sheet. 
Colored  pencils. 

To  study  the  formation  of  alluvial  fans  of  large  area,  and  the  relation  of  such  fans  to  the 
adjacent  topography. 

The  mountains  of  the  west  coast  are  still  rising,  and  being,  therefore,  young  mountains,  the 
processes  of  denudation  are  very  active  on  their  slopes  and  summits.  In  consequence,  the 
streams  which  flow  down  their  slopes  carry  heavy  loads  of  sediment,  and  the  intermont  areas 
of  this  region,  like  the  Valley  of  California,  owe  their  level  floors  to  filling  up  with  this  waste 
from  the  mountains.     (Text-book,  pp.  66-68.) 

On  your  map  of  the  United  States  outline  the  areas  of  the  larger  Piedmont  valleys  of 
the  Pacific  Slope,  as  indicated  on  the  diagram  map.  (It  is  to  be  understood  that  there  are 
many  other  smaller  areas  of  similar  conditions  in  this  region.) 

Between  what  mountain  ranges  are  these  valleys  located?     


What  is  the  approximate 


area  of  each  in  square  miles  ? 


Color  in  with  blue  pencil  (using  the  symbol  indicated  in  the  legend  square  on  the  dia- 
gram map)  the  areas  of  the  Piedmont  valleys  of  the  Pacific  Slope.  Fill  in  the  proper  legend 
square  and  mark  it  Pd.  Val.  Pac.  Slope. 

Study  of  an  Locate  the  position  of  the  Cucamonga  (Cal.)  sheet  on  your  map  of  the  United  States  and 

alluvial  fan  outline  its  area  with  ink.     Letter  in  the  name  of  the  sheet. 

on  the  edge  What  is  the  nature  of  the  country  shown  in  the  northern  part  of  the  Cucamonga  sheet? 

Piedmont 

valley.  

In  the  southern  part?     

What  is  the  approximate  average  slope  per  mile  of  the  stream  in 

i  Cucamonga  Canyon  between  its  source  and  the  point  of  its  disappearance  at  the  edge  of  the 

mountains?     What   is    the   average   slope 

"209 


per  mile  of  the  country  for  five  miles  to  the  south  of  the  mountain  base?     

How  do  these  two  slopes  compare  in  steepness? 


Over  which  slope  could  the  stream  carry  the  greater  amount  of  sediment  ?     

"Why  would  such  a  mountain  stream  be  abundantly  supplied 

with   sediment?     


Why  could  this  sediment  load  not  be  carried  far  beyond  the  edge  of  the 

mountains?      


What  portion  of  the  load  (i.e.  what  kind  of  material)  would  be  deposited 

first?     Why  does  the  stream  disappear  at 

a  short  distance  beyond  the  mountains?     


Account  for  its  reappearance  farther  south. 


What  is  the  significance  of  the  dotted  brown  patches  and  streamers  ? 


Describe  the 
conditions  that  you  think  would  be  observed  in  this  region  at  a  time  when  a  great  flood  poured 


out  from  the  canyon.     

210 


Why  are  such  deposits  as  these  called  alluvial  fans  9 


On  what  portion  of  their  surface 

are  their  slopes  steepest?     Why  there? 

Why  do  the  contours  bend  farthest  outward  directly  opposite  the  stream  mouths?     


Is    the 

climate  on  the  alluvial  fans  arid  or  humid?     

Why,  then,  is  there  such  dense  settlement?     


What  is  the  source  of  the  water  that  these  communities  need  ? 


Human  Give  two  reasons  why  the  towns  are  located  near  the  base  of  the  alluvial  fans  and  away 

occupation. 

from  the  foot  of  the  mountains.     


Write  a  short  paragraph  comparing  and  contrasting  the  mode  of  origin  and  the  slopes 
and  topography  of  a  delta  and  an  alluvial  fan. 


211 


L.— THE   PACIFIC   RANGES   AND   SAN   FRANCISCO    HARBOR 

Materials.  For  Each  Student.  —  The  contour  map  of  the  United  States.    The  San  Francisco  (Cal.)  sheet. 

The  Tamalpais  (Cal.)  sheet.    Colored  pencils. 

Note.  —  It  will  be  well  to  mount  the  two  topographic  sheets  on  cloth  so  that  they  form  one  continuous 
map. 

Purpose.  To  study  the  physical  geography  of  a  mountain  region  along  an  ocean  coast. 

Introduc-  The  mountain  systems  of  the  Pacific  Slope,  west  of  the  Columbia  and  Colorado  Plateaus 

tory-  and  the  Great  Basin,  are  still  being  uplifted  and,  in  consequence,  have  the  topography  and 

characteristics  of  very  young  mountains.  The  uplift  is  not  a  simple  elevation,  but  is  made  up 
of  a  complex  of  movements,  both  up  and  down  vertically,  and  including  also  lateral  shifts  of 
the  mountain  blocks.  Those  parts  of  the  region  which  are  adjacent  to  the  ocean  show  the 
evidence  of  these  movements  most  clearly,  because  the  ocean  furnishes  a  permanent  level,  or 
datum  plane.     (Text-book,  pp.  206,  321.) 

Location  On  your  contour  map  of  the  United  States  outline  the  region  of  the  Pacific  Ranges  as 

and  extent     indicated  on  the  diagram  map. 

ofthe  What  parts  of  what  states  are  included  in  this  region  ?     

region. 

What  notable  differences  are  there  between  the  Pacific  and  Atlantic  coasts  of  the  United 
States?     

Give  a  reason  why  there  is  no  broad  coastal  plain  along  the  Pacific  Coast.    

How  does  the  total  area  of  all  the  high  mountain  provinces  of  the  United  States  compare 
(approximately)  with  the  area  of  the  plain  and  plateau  provinces?     

213 


Did  you,  previous  to  taking  this  course,  conceive  the  mountain  regions  of  the  United  States  to 

be  wider  or  narrower  than  you  have  outlined  them?    

What  reason  can  you  give  for  your  answer?   


Color  in  with  red  pencil  (using  the  symbol  indicated  in  the  legend  square  of  the  diagram 

map)  the  region  of  the  Pacific  Ranges.     Fill  in  the  proper  legend  square  and  mark  it  Pacific 

Ranges. 

Study  of  Locate  the  position  of  the  San  Francisco  and  Tamalpais  (Cal.)  sheets,  and  outline  with 

a  section  of  j_n^  the  area  they  include.     Letter  in  the  names  of  the  sheets. 

f^h°  Have  the  mountains  shown  on  these  sheets  a  rugged  or  a  gentle  topography  ?    

Pacific 

ranges.  Have  the  streams  steep  or  gentle  slopes  ?     


Are  the  small  streams  tributary  to  any  large  system,  or  inde- 
pendent?      What  do  these  facts  indicate 

regarding  the  topographic  age  of  the  region?     

Is  the  coast  line  of    California,   in    general,  high   and  rocky,  or    low  and    sandy  ? 

Is  it,  in  general,  straight  or  indented? 

What  does  such  a  large  irregularity  as  San  Francisco  Bay  indicate 

as  to  the  most  recent  change  of  land  level  in  this  part  of  the  coast?     

How  do  you  account  for  the  flats  on  which 

Oakland  and  Berkeley  are  built  ?    

What  is  the  origin  of  the  narrow  neck   of  land  which  cuts  off  the  mouth  of  the  Bolinas 
Lagoon  ? 


214 


What  does  its  position  indicate  as  to  the  prevailing  direction  of  currents  on  this  coast? 


Human  Why  is  San  Francisco  Bay  an  exceptionally  favorable  site  on  the  Pacific  Coast  for  the 

occupation. 

growth  of  cities? 


How  is  the  site  affected  by  the  fact  that  the  adjacent  mountains  are  growing  ? 


Which  has  the  greater  number  of  docks  for  ships,  Oakland  or  San  Francisco  ? 

Suggest  a  reason  why  San  Francisco,  on  a  peninsula,  has  grown  more  than  Oakland,  on  the 

mainland,  which  has  more  direct  railroad  connections.     


What  effect  has  the  presence  of  the  cities  had  on  the  settlement  of  the  adjacent  mountain 

regions? 

Why  was  a  railroad  built  to  the  summit  of  Mt.  Tamalpais?     

Suggest  reasons  for  the  building  of  several  of  the 

difficult  mountain  roads  of  the  region.      


Write  a  short  paragraph  citing  the  factors  which  make  San  Francisco  Bay  a  very  impor- 
tant harbor. 


215 


LI.— COAST   LINE   CORRELATION 

Materials.  For  Each  Student.  —  The  contour  map  of  the  United  States.    The  Boothbay  (Me.)  sheet.     The 

Barnegat  (N.J.)  sheet.     The  Port  Orford  (Ore.)  sheet. 

For  General  Class  Use.  —  Mt.  Mitchell  (N.C.-Tenn.)  sheet. 

Purpose.  To  gain  an  appreciation  of  the  variation  in  conditions  along  the  coasts  of  the  United  States 

and  the  main  causes  for  this  variation. 

Introduc-  There  are  four  general  variations  in  the  nature  of  coast  lines,  dependent  on  four  variable 

tory.  conditions:  Whether  the  coast  line  is  being  elevated  or  depressed,  and  whether  the  coast 

topography  is  low,  or  bold  and  rugged.    The  length  of  time  that  a  given  condition  has  existed 

also  exerts  a  decided  influence  in  determining  the  character  of  the  coast  line,  as  do  the  nature 

of  the  adjacent  land  areas  and  the  exposure  to  waves  and  currents. 

Study  of  a  Locate  the  position  of  the  Boothbay  (Me.)  sheet  on  your  contour  map  of  the  United  States 

bold,  rocky,   an(j  outline  its  area  in  ink.     Letter  in  the  name  of  the  sheet.     (Text-book,  pp.  208-210.) 

indented 

coast. 


Topog- 
raphy. 


In  what  physiographic  province  is  this  area  located  ? 


What  was  the  rock  structure  of  this  province,  as  noted  in  your  previous  study  ? 


In  what  respects  does  the  topography  of  the  Boothbay  area  differ  from  that  of  the  part  of  this 
province  previously  studied?  


Which  has  the  older  topography  ?_ 

What  is  the  most  notable  characteristic  of  this  coast  ?  _ 


What  is  the  general  direction  of 

the  extension  of  the  long  bays  ("Rivers")?    

Are  the  shores  along  this  coast  steep  or  low?    What  does  this  suggest 

as  to  the  depth  of  the  water  offshore  ?      1 

What  is  the  approximate  average  elevation  of  the  islands  in,  and  the  ridges  between,  the 

217 


long  bays? Are  these  elevations  continuous  ridges 

or  isolated  knobs?  Would  there  be  a  greater  or 

lesser  number  of  islands  if  the  land  surface  were  raised  50  feet?   

If  it  were  depressed  50  feet?  

How  does  this  apply  in  explanation  of  the  present  conditions  along  this  coast  ?    


Why  should  this  be  called  a  drowned  coast  ? 


Human  Give  reasons  why  you  think   this    region  is   attractive    as  a  summer  vacation  resort, 

occupation. 


What  protection  do  the  deep  inlets  afford  vessels  ? 


Why  are  lighthouses  necessary  ? 


What  does  their  location  suggest  as  to  which  is  the  most  important  harbor  of  this  part  of  the 

coast?  Give  a  reason  why  on  this  coast  of 

many  fine  harbors  there  is  no  large  city.      


Study  of  a  Locate  the  position  of  the  Barnegat  (N.J.)  sheet  on  your  United  States  contour  map  and 

low,  sandy    outline  its  area  in  ink.     Letter  in  the  name  of  the  sheet.      (Text-book,  pp.  205  and  212-215.) 
coast. 

°^)g"  In  what  physiographic  province  is  this  area  located? 

Is  the  coast  line  bold  or  low  ?   What  is  the  condition  of  the  valleys  of 

the  larger  streams?  

218 


• 


Does  this  suggest  recent  submergence,  or  uplift,  of  the  land  along  this  coast  ? 


What  would  be  the  effect  of  a  continued  movement  in  the  same  direction  ? 


In  the  other  direction  ? 


What  is  the  origin  of  Island  Beach  ? 


What  is  the  nature  of  the  small  hills  on  its  surface  ? 


Explain  why  the  ocean  side  of  Island  Beach  is  so  straight  and  its  land  side  so  irregular. 


What  do  the  blue-lined  (straight)  areas  represent?     (See  Fig. 20.)    

s. What,   then,  is   taking 

place  in  the  bay  between  Island  Beach  and  the  mainland  ?     

Why  is  a  hook,  extending  west- 
ward, formed  at  Barnegat  Light? 


219 


What  does  its  position  and  extension  suggest  as  to  the 

direction  of  the  current  which  carries  the  sand  supply?      


Does  the  action  of  the  currents  and 

waves  tend  to  straighten  a  coast  line,  or  make  it  irregular?     

Human  What  evidence  is  given  by  the  map  that  the  water  between  the  mainland  and  Island 

occupation. 

Beach  is  quite  shallow?    

r What  kind  of  return  justifies  the  building  of  a  railroad  to  this 

barren  sand  bar?      


Give  some  reasons  why  ocean  bathing  is  much  more  pleasant  here  than  at 

Boothbay,  Me. 


Why  is  this  Barnegat  shore  especially  dangerous  to  navigation  ? 


What  recognition  of  this  fact  do  you  find  on  the  map  ? 


Why  are  the  broad  mouths  of  the 
rivers  not  available  for  harbors?     


220 


Study  of  a  Locate  the  position  of  the  Port  Orford  (Ore.)  sheet  on  your  United  States  map  and  out- 

bold,  reg-      line  its  area  with  ink.     Letter  in  the  name  of  the  sheet.     (Text-book,  p.  206.) 
ular  coast. 

fTopog-  In  what  physiographic  province  is  this  area  located?     

raphy. 

What  are  the  general  characteristics  of  that  province  ?     


To  what  extent  are  they  shown  on 

the  Port  Orford  sheet?     x 

What  is  the  nature  of  the  coast  line  bordering  a  region  of  rising  mountains,  as  here 
shown?      


What  portion  of  the  coast  line  shown  on  this  sheet  rises  directly  and  steeply  from  the  sea  ? 

Which  portion  has  the  most  extensive  coastal 

plain?     How  does  the  presence  of  the  large 

streams  account  in  part  for  the  coastal  plain  ? 


What  conditions  of  the  topography  of  the 

adjacent  land  areas  would  lead  to  a  comparatively  rapid  development  of  a  coastal  plain  along 

this  coast?     


221 


What  does  the  direction  of  the  extension  of  the  bars  along  this  coastal  plain  (and  the  deflec- 
tion  of  the  river  mouths)  indicate  as  to  the  direction  of  the  currents  along  the  coast? 


How  does  the  presence  of  the  streams  tend  to  maintain  openings  in  the  bars  ?    .. 


: Account  for 

the  lakes  along  this  coast.     


Human  What    general    conditions    have    prevented    a    dense    settlement    along    this    coast? 

occupation. 


Account  for  the  location  of  Port  Orford. 


What  effect  must  the   mountains  have  on  the 

future  growth  of  such  a  seaport?     


Why  is  most  of  the  agricultural  settlement  found  on  the 


northern  coastal  plain  and  in  the  valleys  of  the  larger  streams  ? 

222 


Write  a  paragraph  comparing  and  contrasting  the  conditions  of  the  coast  lines  of  the 
three  areas  studied. 


• 

223 


LIL  — SPECIAL  TYPES  OF  LAKES 

Materials.  For  Each  Student.  —  The  contour  map  of  the  United  States.     The  Van  Horn   (Tex.)  sheet. 

The  Crater  Lake  Special  (Ore.)  sheet. 

Purpose.  To  afford  the  pupil  an  opportunity  to  apply  the  methods  of  the  preceding  exercises  in  making 

an  original  interpretation  of  the  features  of  the  above-named  sheets,  and  to  gain  an  incidental 
knowledge  of  two  types  of  lake  basins. 

Introduc-  In  interpreting  the  Van  Horn  (Tex.)  sheet,  see  Text-book,  pp.  87  and  169.. 

t0,7-  For  the  Crater  Lake  (Ore.)  sheet,  see  Text-book,  pp.  121-122. 

Consult  the  references  given  above,  and  then  proceed  to  interpret  the  two  maps  to  the 
best  of  your  ability,  following  the  general  scheme  of  the  preceding  exercises. 


225 


( 


226 


• 


Materials. 


Introduc- 
tory. 


FIELD   EXCURSIONS   FOR   THE   SPRING   SEASON 

LIIL  —  EXCURSION   TO  STUDY  GLACIAL   PHENOMENA 

For  General  Class  Use.  —  One  or  more  magnetic  compasses. 


Purpose.  To  study  the  nature  of  the  evidence  of  the  former  presence  of  glaciers,  and  to  note  some  of  the 

effects  of  former  giaciation. 


If  the  school  lies  outside  the  belt  of  former  continental  giaciation,  this  excursion  cannot, 

of  course,  be  undertaken ;  but  if  it  is  situated  within  the  limits  of  that  belt,  the  probabilities 

are  that  several  of  the  topics  of  this  outline  can  be  included  in  a  single  excursion.     In  some 

regions  two  or  more  excursions  could  be  profitably  devoted  to  this  study. 

Glacial  For  this  part  of  the  excursion  it  is  assumed  that  the  class  is  taken  to  a  rock  exposure  on 

scratches.      which   glacial   striations  are  visible.      Is  the  rock  surface   between  the  striations  rough  or 

smoothed?     .___ What   is  the   width  of    the 

scratches?     Are  they  straight  or  irregular  ?     

i  What  is  their  length  ?     Describe  this  rock 

surface  in  a  few  sentences. 


What  kind  of  a  surface  would  running  water  make  ? 

Weathering?     

What  agency  could 

cause  such  scratches  on  a  rock  surface?     What  is  the  compass 

direction  (approximately)  of  the  scratches?     From  what  direction 

did  the  ice  come  ?     What  effect  will  weath- 
ering have  on  this  rock  surface  ? 

From  the  freshness  of  these  strive,  what  do  you  conclude 

as  to  the  recency  of  the  glacial  period? 


227 


Bowlders  It  is  assumed  that  the  class  is  taken  to  a  place  where  one  or  more  bowlders  of  foreign 

and  peb- 

b  es-  origin  may  be  seen.     What  is  the  nature  of  the  bed  rock  of  the  region  ?     


.. Of   what  kind  of 

rock  is  the  bowlder  composed?    

What  reason  can  you  give  for  the  fact  that  such  glacial 

bowlders  were  given  the  name  erratic  ?    


Do  you  know  where  rock  of  this  kind  is  found  in 

place?     Could  an  ordinary  current  of  water  have  brought  this  bowlder? 

What    agent    of    transportation   could  readily   carry    so   large   a   rock? 

Does  the  place  from  which  the  bowlder  has 

probably  been  brought  agree  with  the  direction  indicated  by  the  glacial  scratches?     

A  till  bank.  It  is  assumed  that  the  class  is  now  examining  a  cut  in  a  deposit  of  till.     In  what  kind  of 

a  water  current,  rapid  or  slow,  is  clay  deposited  ?     In  what  kind  of  a 

water  current  are  pebbles  carried  and  deposited  ?     When  water  de- 
posits sediment,  is  it  assorted  or  unassorted  ?     Is  it  stratified  or  un- 

stratified?     Describe   this   deposit.     I 


Is  it  assorted? 

228 


Is  it  stratified?     Would  water  that  brought  pebbles  also  deposit  clay  at 

the  same  point?     Why  could  water  not  have  formed  this  deposit? 


Could  wind  have  caused  it?     Why? 


Could  ice  have  formed  it? 

Write  a  brief  statement  of  the  differences  between  ice  and  water  as  agencies 
of  transportation  and  deposition.     


Write  a  brief  statement  giving  the  proof  that  this  deposit  was  not  made  by  water,  but  by  ice. 


Examine  the  pebbles  in  the  till  to  see  if  they  are  all  the  same  kind  as  the  bed  rock  of  the  region. 


Are  any  of  them  scratched  ?     Describe  the  scratched  stones,  and  tell  how 

they  could  have  been  scratched  if  brought  by  a  glacier.      

229 


What  is  the  form  of  stream  pebbles? 

Are  stream  pebbles  scratched  ?     What  light  do  the  scratched  stones  throw 

upon  the  origin  of  this  till  deposit? 


Write  a  paragraph  stating  the  evidences  that  you  have  seen  indicating  the  former  presence 
of  an  ice  sheet  in  this  region,  and  the  reason  for  concluding  that  these  phenomena  cannot  be 
assigned  to  other  agencies,  such  as  wind  or  running  water. 


Other  gla-  If  other  glacial  phenomena,  such  as  moraines,  drumlins,  kames,  eskers,  or  outwash  gravel 

cial  phe-        plains  are  studied,  note  their  position,  form,  and  composition.    State  their  origin,  with  reasons 
nomena. 

for  the  conclusion.     


230 


LI V.—  EXCURSION  TO  STUDY  RIVER  VALLEY  DEVELOPMENT 

Materials.  For  Each  Student.  —  The  topographic  map  of  the  region,  if  published. 

Purpose.  To  study  the  form  and  stage  of  development  of  a  valley  in  the  home  region;   to  interpret  its 

past  history  ;  and  to  gain  an  appreciation  of  the  probable  changes  in  the  future. 

Introduc-  For  the  purpose  of  this  excursion  a  valley  of  moderate  size  is  better  than  a  large  one. 

tory.  (Even  a  gully  in  a  field  would  serve  for  such  an  excursion,  though  it  would  then  be  necessary 

to  modify  this  outline.)     There  would  be  no  disadvantage  in  going  to  the  same  valley  as  that 

studied  in  section  XII. 

The  valley  Where  does  the  stream  rise?.    

form. 

Where  is  the  mouth  ?     

About  how  long  is  it? 

To  what  is  it  tributary?     

About  how  wide  is  its  valley  ?     About  how  deep  is  the  valley  ? 

What  is  the  nature  of  the  divide  (sharp,  flat,  etc.)  between  this 

valley  and  the  next  one  ?     Are  the  sides  of 

the  valley  steep  or  gently  sloping?     ._ 

If  the  sides  are  different  in  different  parts,  state  the 

nature  of  the  difference. 


Has  the  valley  form  the  characteristics  of  youth,  maturity,  or  old  age?     

Is  there  greater  or 

less  maturity  toward  the  mouth  of  the  stream  ?    '_ 

Thestream.  About  how  wide  is  the  stream  ? How  does  this  compare  with 

the  width  of  the  valley? 

^^  Is  the  stream  ever  larger?     About  how 

much?    Are  there  flood  plains  ?     


231 


Is  the  course  meandering?     Does  the  stream  flow  on  bed  rock 

anywhere?     Are  there  any  lakes  in  this  valley  ?     

Are  there  falls  or  rapids? 

What  evidence,  if  any,  is  there  that  the  stream  is  enlarging  its  valley  either 

laterally  or  vertically?     


What  evidence,  if  any,  is  there  that  the  stream  is  aggrading  its  valley?. 


What  does  the  condition  of  the  stream  and  its  relation  to  the  valley  indicate  as  to  the  age 
stage  of  the  valley? 


Processes  In  what  part  of  its  valley  does  a  young  stream  cut  most  rapidly  ? 

of  valley 

formation. 


the  valley  form  if  this  were  the  only  process  in  valley  formation  ? 

232 


What  would  be 


How  does  weathering  aid 

in  valley  widening?     


How  does  the  stream  itself  tend  to  widen  its  valley  ? 


Which  is  the  more  rapid,  the  verti- 


cal cutting  by  the  stream,  or  weathering?     

Which,  therefore,  represents  the  longer  time  for  its  formation,  a  broad  valley  or  a  gorge  valley  ? 

Apply  these   conclusions  in   proving  your 

previous  statement  about  the  age  stage  of  this  valley.     


• 


Rate  of  Have  you  ever  observed,  or  heard  of  any  change  in  the  form  of  this  valley?     

valley  for- 
mation. 

Are  visible  changes  to  be  expected  in  a  year  ?     In  ten  years  ?    

In  a  thousand  years?     Is  the  rate  of  valley  formation  rapid  or  slow? 

About  how  much  material  has  been  removed  from  the  valley  where 

you  stand  ?  Answer  by  filling  out  the  following  sentence  :   A  depth  of  about 

feet,  and  a  width  of  about 1 feet  (or  miles).     Where  has  all  this  material 

gone?     

Is  the  stream  always  carrying  sediment?     Write  a  brief  paragraph  stating 

what  you  conclude  as  to  the  rate  of  valley  formation  and  the  time  required  to  form  such  a 


valley  as  this  one.     

233 


The  future  Will  the  stream  continue  to  erode  this  valley  deeper?      Where  is  its 

of  the  val- 

ley>  base  level  ? r__—r 

Can  it  erode  below  that?    _ Will  weathering 

continue?    Will  its  rate  increase  or  decrease ?    

Write  a  brief  paragraph 

telling  what  you  consider  to  be  the  future  of  this  valley,  if  no  accident  intervenes,  giving  rea- 
sons for  your  conclusions. 


234 


LV.— EXCURSION  TO  STUDY  THE  GENERAL  PHYSIOGRAPHY  OF  THE 

REGION 

Materials.  For  Each  Student.  —  The  topographic  map  of  the  region,  if  published. 

Purpose.  To  gain  an  appreciation  of  the  physiographic  features  of  the  home  region;  its  topography, 

drainage,  and  cultural  relations. 


Introduc- 
tory. 


Topog- 
raphy. 


If  possible,  these  observations  should  be  made  from  some  elevated  view  point,  such  as  the 
top  of  a  hill  overlooking  the  surrounding  region,  or  a  tower  which  affords  a  broad  outlook. 
Failing  such  a  vantage  point,  it  may  still  be  possible  to  find  a  site  from  which  the  general 
topography  of  the  region  can  be  appreciated  and  studied. 

What  great  class  or  classes  of  rocks  have  you  observed  in  this  region  ?    


If  sedimentary, 


are  the  layers  horizontal  or  inclined  ? 


What  can  you  infer  from  this  as  to  the  former  con- 


dition of  the  region  ? 


What  marked  changes  have  occurred  in  the  region  since  the  time  of 

the  formation  of  the  rocks?     


What  is  the  topographic  form  of  the  region,  i.e.   is  it  a 

plateau,  flood  plain,  mountain  valley,  etc.?     ■. 

235 


What  is  the  elevation  above  sea  level  of  the 

place  on  which  you  are  standing,  as  shown  by  your  topographic  sheet?     

Locate  and  give  the  names  and  elevations  of  any  other  hills  or 

summits  which  are  visible  and  are  shown  on  your  map.     


What  can  you  say  regarding  their 

origin  and  history  ?     


Drainage.  Locate  and  name  the  largest  stream  of  the  region. 


Is  it  a  continuous  or  an  intermittent 

stream?     j What  is  the   source  of   its  water 

supply?     


To  what  drainage  system  does  it  belong  ? 

236 


What    tributaries    has     the    main 

stream  of  this  region?     


Has  the  main  stream  a  straight  or  meandering  course  ? 
Is  it  cutting  down  or  building  up  its  channel  ? 


How  do  you  explain  this  condition  ? 


What  is  the  topographic  age  of  the  stream  valleys, 

—  young,  mature,  or   old?     : Describe    their 

form  to  show  what  you  mean  by  applying  such  a  term  to  them.      


Are  there  any  lakes,  and  if 

so,  what  caused  them?     


237 


Human  What  was  the  main  physiographic  factor  which  led  to  the  establishment  and  growth  of 

occupation. 

the  community  in  which  you  live? 


What  is  the  bearing  of  the  fact  that  the  mainstream  is 

navigable  or  not  navigable? 


That  the  region  is  level,  hilly,  or  mountainous  ? 


What  has 

been  the  influence  of  the  topographic  age  of  the  valleys  on  the  growth  and  development  of  the 


region  ? 


What  are  the  main  lines  of  transportation  and  travel  ? 


In  what  ways  have  these 

been  influenced  or  determined  by  the  topography  ?     


238 


Is  the  climate  of  the  region  humid,  dry, 

or  arid?     What  has  been  the  effect  of  the 

climatic  conditions  on  the  human  occupation  of  the  region?     


Is  the  region  an  agricultural, 

grazing,  mining,  or  manufacturing  district?     

What  physiographic  factors  have  determined 

this?     "_ 


Write  a  short  paragraph  stating  the  influence  of  the  physiography  on  the  settlement, 
present  occupation,  and  development  of  the  region  in  which  you  live. 


239 


• 


THE   OCEAN 
LVI.     OCEAN   CURRENTS 

Purpose.  To  study  the  cause   of  the   system  of  ocean   currents,   and  to   note   the   influence   of  the 

currents  on   temperature. 


Relation  of  Figure  22  is  a  chart  showing  the  system  of  ocean  currents  in  the  oceans  of  the  world ; 

ocean  cur-      ant\  Figure  40  (p.  329)  shows  the  prevailing  winds  over  the  oceans.     In  each  case  the  arrows 

rents  to         point  in  the  direction  of   motion  of   the  water  or  air.     Compare  these  two  charts  to  see 
winds 

how    they    resemble    each    other.      For    instance,   how    does    the   ocean   current   south    of 

Australia,   South  America,  and   Africa  compare  with  the  wind  direction   in  that  region? 


How  do  the  winds  and  currents  agree  in  the  northern  Atlantic  and  Pacific  ? 


Why  is  the  current  in  the  southern  hemisphere  more  regular  than  that  in  the  northern  ? 


What  is  the  direction  of   winds  in  the   tropical   zone   on   each  side  of   the   equator  ? 


How  does  the  motion  of  the  ocean  waters  correspond  to  this  ? 


What  effect  have  the  continents  on  the  ocean  currents  ?. 


If  you  were  to  blow  on  the  surface  of  a  pan  of  water,  which  way  would  the  water  move  ? 


241 


What  must  be  the  effect  of  the  steady  blowing  of  the  wind  in  one  direction  over  a  large  body 
of  water  like  the  ocean  ?     

From  your  study  of  the  wind  and  ocean  current  charts,  state  the  primary  cause  of  the  ocean 
currents.     


fw 


/ 

/  / 


TTPfc 


m 


QWv4l\    \         \    GREENLAND    J  7# 


R  C^T  J  C 


jn&mtf'- 


OCEAN 


VA     ;aCStWia/V///,         ~^J\\?Xs 


?/«  s 


•^m^ 


-mi 


^Ma^5ra 


OCEAN 


,*wT 


120  °  Longitude  East  IliO  ' 


160'  Longitude  W„t         120" 


80°         Longitude  Weft      40°     from  Greenwich  0°       Longitude  E«tt  40° 


The  ocean 
eddies. 


Fig.  22. —  A  Chart  showing  the  Principal.  Ocean  Currents  and  Ocean  Drifts  in  the  World. 

On  the  chart  (Fig.  22)  locate  two  great  eddies  in  the  Atlantic  Ocean  and  two  in  the 
Pacific.     On  which  side  of  the  equator  does  each  lie?     


242 


Selecting  one  in  the  northern  hemisphere,  describe  the  motion  of  water  in  it,  e.g.  "  it  flows 
southwest,  then  west,  then" 


In  other  words,  the  direction  of  the  current  is  constantly 

turning.     Going  with  the  current,  which  way  is  it  turning,  toward  the  right  or  toward  the  left  ? 


The  effect  of  the  earth's  rotation  tends  to  turn,  or  deflect,  all  moving  bodies  toward  the  right  in 
the  northern  hemisphere.     Study  the  eddies  in  the  southern  hemisphere,  and  state  in  which  way 

the  currents  are  deflected  in  that  hemisphere.     


Warm  and  In  the  northern  hemisphere,  is  a  current  from  the  south  warm  or  cold,  as  compared 

cold  cur- 
rents. 

to  the  ocean  water  on  either  side  of  it?     

How  about  a   current  from  the  north  ?    

Is   the   Labrador   current   cold   or  warm?     " 

The    Gulf     Stream? The    west    wind    drift? 

Which  side  of  the  North  Atlantic  has  the 

warmer  water,  the  American  or  the  European?    ___. 

Locate   cool   currents   in   the   southern    hemisphere    and   state    their   position    and    cause. 


What  effect  on  the  temperature  of  the  tropical  oceans  must  the  movement  of  ocean  currents 

have?    

What  effect  on  the  temperature  of  the  Arctic  regions  must  the  movement  of  the  ocean  currents 

have?     

243 


Currents  from  which  ocean,  the  Atlantic  or  Pacific,  have  the  greatest  effect  on  the  Arctic  ? 

Trace  the  southern  limit  of  icebergs  in  the  North 

Atlantic.    On  which  side  does  the  ice  float  farthest  south?    

Explain  this.     *< 


Of  what  importance  is  the  fact  that  icebergs  come  down  across  the  path  followed  by  the 
transatlantic  steamers  ?   


Fogs  are  caused  by  damp  winds  blowing  from  warm  to  cool  regions.     Knowing  this,  and 
by  the  aid  of  the  ocean  current  chart,  explain  why  the  ocean  near  Newfoundland  is  one  of  the 

foggiest  places  on  the  earth. 


Effect  of  Why  cannot    the    ocean    currents   themselves  affect    the    temperature    of    the    land  ? 

ocean  cur- 
rents on 
the  temper- 

the  land        What  must  help  to  carry  their  influence  to  the  land?    

What  is  the  prevailing  wind  direction  in  the  British  Isles?    1 

State  why  the  climate  of  the  British  Isles  is  much  warmer  than  that  of  southern  Labrador, 

which  lies  in  the  same  latitude.    


Are  east  winds  on  the  coast  of  New  England  warmed  or  cooled  in  passing  over  the  adjacent 

ocean  current  ?     How   about  winds   from  the 

south  in  the  New  England  region?     State  as 

fully  as   you   can   how   the   ocean   currents   influence  the   climate  (a)  of  northern   Europe ; 

244 


(b)  northeastern  United  States ; 


and  (c)  northwestern  United  States  and  Alaska. 


On  the  blank  chart  (Fig.  23)  sketch  from  memory  the  great  eddies  and  the  principal 
currents  of  the  oceans,  giving  their  names. 


245 


« 


247 


€ 


LVIL  —  TIDES 

Purpose.  To  study  the  rise  and  fall  of  the  tides  at  a  given  place  in  order  to  learn  the  time  between 

tides,  the  variation  in  height  of  tides,  and  their  relation  to  the  moon's  phases;  also  to  learn  the 
cause  of  tidal  currents. 


TIDES   AT   EASTPORT,   ME. 

,   SEPTEMBER 

High  Tides 

Low 

Tides 

a.m. 

P.M. 

A. 

M. 

p 

M. 

Date 

Time 

Height  in  Feet 

Time 

Height 

Time 

Height 

Time 

Height 

h.  in. 

h.  m. 

h.  m. 

h.  m. 

1 

2.01 

18.6 

2.25 

18.7 

8.10 

-0.2 

8.41 

-0.5 

2 

2.54 

17.8 

3.14 

18.0 

9.01 

0.7 

9.38 

-0.1 

3 

3.50 

17.0 

4.15 

17.4 

10.00 

1.5 

10.40 

0.7 

4 

4.52 

16.3 

5.19 

17.0 

11.03 

2.0 

11.46 

0.9 

5 

6.00 

16.0 

6.26' 

17.1 

12.11 

2.1 

6 

7.08 

16.1 

7.31 

17.5 

0.54 

0.7 

1.18 

1.8 

7 

8.11 

16.8 

8.32 

18.2 

1.56 

0.2 

2.21 

1.1 

8 

9.08 

17.6 

9.28 

19.0 

2.55 

-0.5 

3.17 

0.1 

9 

9.59 

18.3 

10.18 

19.4 

3.45 

-1.2 

4.08 

-0.6 

10 

10.43 

19.0 

11.04 

19.7 

4.34 

-1.5 

4.54 

-1.2 

11 

11.27 

19.3 

11.48 

19.5 

5.16 

-1.6 

5.37 

-1.4 

12 

12.08 

19.2 

5.58 

-1.4 

6.20 

-1.3 

13 

0.30 

19.0 

12.49 

18.9 

6.38 

-0.8 

7.02 

-0.8 

14 

1.12 

18.3 

1.30 

18.2 

7.18 

0.0 

7.43 

-0.1 

15 

1.54 

17.4 

2.12 

17.4 

8.00 

1.0 

8.28 

0.7 

16 

2.38 

16.4 

2.56 

16.6 

8.42 

2.0 

9.15 

1.5 

17 

3.25 

15.5 

3.43 

15.9 

9.30 

2.9 

10.07 

2.2 

18 

4.16 

14.8 

4.37 

15.3 

10.23 

3.6 

11.02 

2.5 

19 

5.12 

14.4 

5.34 

15.1 

11.21 

3.9 

11.58 

2.6 

20 

6.10 

14.4 

6.31 

15.4 

12.20 

3.7 

21 

7.08 

15.0 

7.26 

16.0 

0.55 

2.2 

1.16 

3.1 

22 

8.00 

15.9 

8.18 

16.9 

1.48 

1.5 

,    2.11 

2.1 

23 

8.48 

16.9 

9.07 

17.9 

2.38 

0.7 

2.58 

1.0 

24 

9.32 

17.9 

9.53 

18.8 

3.22 

-0.2 

3.44 

-0.1 

25 

10.16 

18.9 

10.38 

19.4 

4.08 

-1.0 

4.27 

-1.1 

26 

10.59 

19.6 

11.22 

19.7 

4.49 

-1.5 

511 

-1.8 

27 

1142 

20.0 

5.31 

-1.7 

5.55 

-2.1 

28 

0.08 

19.8 

12.26 

20.0 

6.15 

-1.5 

6.41 

-2.1 

29 

0.54 

19.6 

1.13 

19.7 

7.00 

-1.0 

7.30 

-1.7 

30 

1.42 

18.9 

2.04 

19.1 

7.48 

-0.3 

8.23 

-1.1 

249 


Figure  24  is  a  diagram  showing  the  rise  and  fall  of  the  tides  at  Eastport,  Me.,  for  the 
first  15  days  of  September  during  a  certain  year.  At  the  top  of  the  diagram,  the  figures  12, 
6,  12,  6,  12,  etc.,  represent  hours  of  the  day,  the  first  12  being  midnight,  the  second  12  noon, 
the  third  12  midnight  again,  etc.  The  first  6  is  6  o'clock  in  the  morning;  the  second  6  is- 
6  p.m.  Each  of  the  vertical  lines  of  the  cross-section  paper  represents  two  hours  of  time.  On 
the  right  and  left  margins  the  figures  0,  5,  10,  15,  20,  etc.,  represent  feet ;  and  each  horizontal 
line  of  the  cross-section  paper  stands  for  1  foot.  The  zigzag  line  represents  the  rise  and  fall 
of  the  tide  for  the  first  15  days  of  the  month.  Study  this  diagram  until  you  understand  it. 
Notice,  for  example,  in  the  tide  table  for  this  month,  printed  below,  that  the  first  high  tide 
of  Sept.  1  came  at  2.01  a.m.,  and  reached  a  height  of  18.6  feet;  the  second  high  tide 
came  at  2.25  p.m.,  and  reached  a  height  of  18.7  feet;  the  first  low  tide  came  at  8.10  a.m. 
and  its  elevation  was  —0.2  foot;  the  second  low  tide,  at  8.41  p.m.,  stood  at  —  0.5  foot.  In 
making  the  diagram,  four  dots  were  placed  in  the  proper  positions  under  Sept.  1,  two  for 
the  high  tides  and  two  for  the  low.  These  were  then  connected  by  the  lines.  The  same  pro- 
cedure was  followed  for  each  of  the  other  days. 

In  the  table  on  page  467  are  data  for  the  completion  of  the  diagram  (Fig.  24).  Place  dots 
in  the  proper  positions  for  the  last  fifteen  days  of  September,  and  then  connect  them  with  lines. 
You  then  have  a  diagram  showing  the  rise  and  fall  of  the  tides  at  one  place  for  a  month. 


How  many  high  {flood)  and  low  (ebb)  tides  are  there  each  day  ? 

From  the  table,  determine  the  exact  length  of  time  between  flood  and  ebb  tide  on  a  certain 

day.     - Between  ebb  and  flood  tide.     

. Between  two  successive  flood  tides.     


Between  two  successive  ebb  tides. 

Between  the  flood  tides  of  successive  days. 


If  the  flood  tide  were  to  reach  its  greatest  height  at  12  o'clock,  noon, 

on  Sept.  10,  at  what  time  (approximately)  would  it  reach  its  greatest  height  on  Sept.  11  ? 


On  Sept.  15  ? 


Height  of  What  is  the  range  (in  feet)  between  the  high  and  low  tide   on   Sept.   1  ? 

the  tide. 

Find  a  day  in  which  the  range  is  greater  than  this.     


Find  one  in  which  the 


range  is  less. 


How  many  periods  of  high  range  of  tide  are  there  in  this  month  ?      ___ 

How  many  of  low  range  of  tide  ?     

Between  what   days  of   the  month  is   the  tidal   range   high? 


250 


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§ 


Between  what  days  is  it  low  ? 


moon? 


Which  two  of  these  periods  correspond  with  new  and  full 


quarters  of  the  moon  ? 


Which  two  with  the  first  and  last 


Which  of  these  are 

the  spring  tides  (see  Text-book,  p.  189)?     

Which  are  the  neap  tides?     

Are  the  sun  and 

moon  more  nearly  in  line  at  new  and  full  moon,  or  at  the  quarters  ?      

What  does  the  relation  between  moon  and  tidal  range  suggest  as  to 

the  cause  of  tides? 


Tidal  cur-  The  tide  causes  a  gradual  rise  and  fall  in  the  level  of  the  ocean.     It  is  essentially  a  ver- 

rents.  tical  movement ;  but  under  some  conditions  the  tide  causes  horizontal  movements,  which  are 

called  tidal  currents.   (Text-book,  pp.  187-189.)    In  the  diagram  (Fig.  25)  the  tide  rises  4.6  feet 

on  one  side  of  the  island,  and  4  feet  on  the  other  side.     What  will  be  the  movement  of  water 


through  the  strait  (s)  at  high  tide  ? 


If  the  tide  rose  to  a  height  of  4  feet  on  both  sides  of 

the  island,  but  high  tide  came  a  half  hour  later  on  one  side  than  on  the  other,  what  would  be 


the  result  in  the  strait  (s)  ? 


• 


253 


Fig.  25. —  To  show  Differences  in  Height  of  Tide  at  Different  Points. 
How  would  such  tidal  currents  affect  the  movements  of  ships  ? 


The  transportation  of 


sand  and  other  sediment? 


When  the  currents  move  swiftly,  they  can  carry  much  sedi- 
ment.    What  must  happen  when  the  current  is  checked  ? 


254 


• 


Materials. 


Purpose. 

The  air  has 
substance. 


THE  ATMOSPHERE 
LVIII.  —  THE  ATMOSPHERE  HAS  SUBSTANCE  AND  WEIGHT 

For  Each  Student.  —  A  drinking  glass.    A  piece  of  candle. 

For  General  Class  Use. — Air  pump.    A  glass  cylinder  open  at  both  ends.    A  glass  tube  35  inches 
long  sealed  at  one  end.    A  bottle  of  mercury.    A  glass  funnel.    A  ruler. 

To  show  that  the  atmosphere  Jias  substance  and  weight;  also  the  principle  of  the  barometer. 

What  resemblance  is  there  between  a  balloon  floating  in  the  air  and  a  boat  floating  on  the 

water? :  


Why  does  the  balloon  float? 


What  is  the  difference  between  water  and  air  to  sight  ? 


Could  a  bird  fly  if  the  air  were  not  a  real  substance?     Could  a  sailboat 

move  along?     Would  a  windmill  be  turned?     

Give  other  proofs  that  the  air  is  something  real.     


The  air  is      What  takes  place  when  a  match  burns? 

a  mixture 

of  gases.         ^ 


Would  it  burn  more  or  less  rapidly  if  the  air  were  all  oxygen?      

All  carbon  dioxide  ?     Light  a  small  piece  of  candle,  and  over  it  set 

an  upturned  glass.     Note  what  happens.     T 


255 


Explain  why  the  candle  light  went  out. 


Why  is  a  lamp  chimney  made  with  an  opening  at  both  the  top  and  bottom  ? 


Make  a  list  of  the  other   substances   of   which  the  air  is  composed.     (Text-book,  p.  229.) 


The  air  Why  must  all  substances  on  the  earth  have  weight ' 

has  weight. 


Why,  then,  must  the  atmosphere  also  have  weight  ? 


Place  a  glass  cylinder,  open  at  both  ends,  on  the  air  pump.     Press  the  palm  of  your  hand  on 
the  upper  end  of  the  cylinder.    Pump  out  the  air  from  beneath  your  hand.    What  is  the  effect  of 


the  air  above  your  hand ' 


Why  do  you  not  ordinarily  feel  the  weight  of  the  air? 


How  much  Two  members  of  the  class  perform   this   experiment,   the   others  watching  closely  and 

the  air  answering  the  questions  below.     One  of  the  experimenters  stands  the  glass  tube  on  its  closed 

weighs. 

end.     What  fills  the  tube?     The  other  experimenter  carefully  fills 

the  tube  with  mercury,  using  the  glass  funnel.     What  now  fills  the  glass  tube  ?     

256 


Into  a  drinking  glass  pour  mercury  enough  to  fill  it  to  a  depth  of  two  inches.  The  student 
holding  the  glass  tube  now  puts  his  thumb  firmly  over  the  open  end  of  the  tube,  turns  the 
tube  upside  down,  thrusts  the  end  beneath  the  mercury  in  the  glass,  and  then  removes  his 

thumb.    What  happens  ?     


The  other  experimenter  next  measures  the  height  of  the  mercury  in  the  tube,  measuring  from 
the  surface  of  the  mercury  in  the  glass.     How  many  inches  long  is  the  column  of  mercury  ? 

What  is  above  it?     Why  does  the  mercury 

not  drop  out  of  the  tube?     


The  result  would  have  been  the  same  if  the  tube  had  been  a  foot  square,  or  an  inch  square, 
or  any  size.     Fill  out  the  following  sentence.     The  weight  of  a  column  of  air  is  equal  to  the 

weight  of  a  similar  column  of  mercury     inches  high.     A  column  of 

mercury  1  inch  square  at  the  base  and  1  inch  high  weighs  approximately  \  pound.     How  much 

would  a  column  of  mercury  1  inch  square  and  30  inches  high  weigh  ?     

How  much,  then,  is  the  weight  of  a  column  of  air  1  inch  square?     

Fill  out  the  following  sentence.     The  pressure  of  the  atmosphere  is  equal  to 

pounds  on  every  square  inch. 

The  barom-  The  apparatus  just  used  is  a  rough  form  of  barometer.     Could  water  or  other  liquids  be 

eter. 

used  in  a  barometer?     If  water  were  used,  would  the  column  in  the  tube  be 

higher  or  lower  than  the  mercury  column  ?     Why  ? 


Why  is  mercury  the  best  adapted  liquid  for  use  in  barometers  ? 


257 


For  what   purpose   is   the 

barometer  used?  4 


If  there  is  a  mercurial  barometer  in  the  school,  examine  it  carefully  and  make  a  drawing  of  it, 
naming  the  important  parts.  Watch  the  barometer  for  the  next  few  days  to  see  if  the  column 
of  mercury  remains  always  at  exactly  the  same  height.     Keep  a  record  of  your  observations. 


What  do  they  show  about  the  weight,  or  pressure,  of  the  air  ? 


< 


258 


Materials. 


Purpose. 


The  ther- 
mometer. 


LIX.  —  THE  THERMOMETER,  AND  THE  DAILY  RANGE  OF  TEMPERATURE 

For  Each  Student.  —  Ruler.    Sharp  pencil. 

For  General  Class  Use.  —  One  or  more  thermometers. 

To   understand   the  thermometer;   to  interpret   the   daily  range  of  temperature;    and  to 
study  the  effect  of  inclination  of  the  sun's  rays. 

Examine  the  thermometer.     What  is  in  the  space  above  the  mercury?     '_ 

If  air  were  there,  would  the  mercury  rise  and  fall  so  easily? 

Why  does  not  the  mercury  rise  30  inches,  as  in  the  barometer?     


Does   the 

mercury  in  the  thermometer  rise  or  fall   when   warmed?     Why? 


State  and  explain  the  movement  of  the  mercury  when  cooled. 


Could  other  liquids  besides 

mercury  be  used  for  thermometers?    

Fill  out  the  following  sentence:     Liquids  expand  when  warmed  and 

when  cooled.      Find  out  if  the  same  is  true  of  gases  and  solids.     


Fahrenheit 
and  Centi- 
grade 
scales. 


If  your  thermometer  is  graduated  according  to  the  Fahrenheit  scale,  what  is  its  boiling  point  ? 

Its  freezing  point  ?    How  many  degrees  are  there  between  the 

boiling  and  freezing  points  ?     By  the  Centigrade  scale,  freezing  point  is  called  0° 

and  boiling  point  100°.     How  many  degrees  of  Centigrade  are  equal  to  1°  of  Fahrenheit  ? 1 

Explain  why  it  is  true  that  to  change  Centigrade  to  Fahrenheit  scale  you  multiply   by  1.8  and   add  32. 


259 


Change  10°  Centigrade  into  Fahrenheit  degrees. 


Change  25°  Centigrade  into  Fahrenheit. 


Making  a 
curve  to 
show  daily 
range  of 
tempera- 
ture. 


Below  is  printed  a  record  of  the  temperature  for  every  two  hours  on  a  winter's  day  (Feb. 
19),  in  a  city  in  northern  United  States.  In  the  diagram  (Fig.  26)  each  of  the  horizontal  lines 
represent  1°,  and  each  of  the  vertical  lines  2  hours.  Make  a  cross  to  indicate  the  degree  of 
temperature  for  each  two  hours  (as  shown  in  Fig.  26).  Then  connect  the  centers  of  these 
crosses  with  a  line. 


A.M. 


P.M. 


Midnight 
21° 

2 
25° 


Temperature  record  for  one  day. 


20° 

4 

25.5C 


19° 

6 
24° 


6 
18.9° 

8 
23.2° 


18.8° 

10 

22° 


10 

20.8° 

Midnight 
20° 


Noon 
23° 


A.M. 


P  M. 


Study  of 
the  daily 


Midnight                                                                                  Noon                                                                                 Midnight 

12        2         4         6         8        10       12        2         4         6         8        10      12 

\ 

f 

/ 

y 

/ 

\ 

Fig.  26. 


26° 
25° 
24° 
23° 
22° 
21° 
20° 
19° 
18° 
17° 


If  possible  make  a  similar  curve  (on  the  accompanying  sheet  of  cross-section  paper)  representing  local 
conditions.  Data  can  be  secured  from  the  nearest  Weather  Bureau  office,  or  from  a  self-registering  thermom- 
eter. Failing  such  records,  the  pupils  themselves  may  supply  data,  one  pupil  being  sent  to  observe  the  tem- 
perature every  two  hours,  during  school  hours,  and  volunteers  bringing  data  from  home  for  the  evening  and 
early  morning. 

At  about  what  hour  of  the  day  was  the  temperature  lowest? 

Highest?    Why  does  the 


warmest  period  come  after  midday  ? 


260 


The  coldest  after  midnight? 


Making  a  On  the  cross-section  paper  make  a  curve  similar  to  that  previously  made,  to  show  thi 

daily  curve    range  of  temperature  for  a  summer  day.     Following  are  data  for  such  a  curve,  representinj 
for  summer.  ^e  temperatures  for  July  10  in  a  northern  city. 


A.M. 


Midnight 
60° 


2 

56° 


4 

55.4° 


6 

57° 


65° 


10 

74° 


Noon 
80° 


P.M. 


2 

85° 


4 

83° 


6 
79° 


8 
73c 


10 

66° 


Midnight 
61° 


Compari- 
son of  the 


Why  is  it  warmer  at  midday  in  summer  (as  shown  in  the  diagram  just  drawn)  than  a 
two  daily      midday  in  winter  (as  shown  in  the  diagram  for  the  winter  day)  ? 


curves. 


Why  warmer  during  the  night  ? 


In  which  of  the  diagrams  is  there  greatest  range  between  lowest  and  highest  temperatures 


Why  is  this  true  ? 


How  do  the  two  curves  resemble  each  other  ? 


Fill  out  the  following  sentence :   In  both  summer  and  winter  the  temperature  is 


Variatioo 

in  amount 

of  heat  at  midday  than  late  in  the  afternoon;  and  the  temperature  is 

from  the        jn  sumrQer  than  in  winter.     What  relation  do  these  facts  have  to  the  altitude  of  the  sun 
sun. 


261 


To  understand  the  reason  why  the  altitude  of  the  sun  influences  the  temperature,  draw  two 
diagrams,  as  follows : 

Diagram  1.   On  the  cross-section  paper,  mark  heavily  two  of  the  vertical  parallel  lines  an 
inch  apart  down  to  a  certain  horizontal  line.     How  many  spaces  do  these  vertical  parallel  lines 

include  at  the  horizontal  line?     Starting  from  the  same  horizontal 

line,  draw  parallel  lines  (an  inch  apart),  each  at  an  angle  of  45°  with  the  horizontal  liue.     How 

many  spaces  are  included  between  these  two  parallel  lines  at  the  horizontal  line  ? 

If  these  parallel  lines  in  both  cases  represent  rays  of  the  sun,  and  the  horizontal 

line  the  surface  of  the  earth,  in  which  case  would  a  given  area  receive  most  rays  ? 

How  does  this  help  to  explain  the  fact  that  the  sun  warms  the  earth  more  at  midday  than  in 
the  afternoon  ? 


In  summer  more  than  in  winter  ? 


Diagram  2.     In  the  diagram  (Fig.  27)  draw  two  lines,  one  vertical,  the  other  at  an  angle 
of  45°,  both  passing  through  the  atmosphere  to  the  same  point  on  the  surface  of  the  earth 


ATMOSPHERE 


Fig.  27. 


(marked  A).     Let  each  line  represent  a  ray  of  sunlight.     Measure  with  the  ruler  to  see  in 
which  case  the  ray  passes  through  a  greater  thickness  of  air.     Which  ray,  then,  would  be  most 

interfered  with  in  its  passage  through  the  air?     

How  does  this  help  to  explain  (a)  the  fact  that  the  sun  is  warmer  at  noon  than  in  the  after- 


noon (• 


262 


(b)  that  it  is  warmer  in  summer  than  in  winter  ?      

(c)  that  you  can  often  look  directly  at  the 

sun  just  before  sunset?     

Now  state,  clearly  and  concisely,  why  the  sun's  rays  are  warmer  in 

summer  than  in  winter,  and  at  noon  than  in  the  afternoon.     


263 


4 


LX.— WEATHER   OBSERVATIONS 

Materials.  For  General  Class  Use.  —  One  or  more  thermometers.    A  barometer.    If  possible,  other  meteoro- 

logical instruments. 

Purpose.  To  study  local  weather  conditions. 

Value  of  Work  of  this  nature  will  teach  the  use  of  the  instruments ;  it  will  direct  the  student's  at- 

such  a  tention  to  the  weather  phenomena  that  are  always  surrounding  him ;  it  will  supply  original 

s  u  y'  data  for  later  use,  especially  in  the  study  of  weather  maps.     For  a  part  or  all  of  the  time  that 

the  class  is  studying  the  atmosphere  a  weather  record  may  profitably  be  kept,  using  such  in- 
struments as  the  school  possesses. 
How  to  For  at  least  one  week,  at  the  same  hour  if  possible,  let  each  student  make  observations  of 

keep  the        ^e  weather  conditions  and  fill  in  the  blank  spaces  in  the  table.     After  that,  let  a  different 
record 

student,  each  day,  make  the  observations  and  report  them  to  the  class  for  entry  in  their  tables. 


265 


i 


Date 

Day  of 
Week 

Hour 
of  Day 

Tem- 
pera- 
ture 

Baro- 
metric 
Pressure 

Wind  Direction 

Wind  Velocity 

Kinds  of  Clouds 

Rain  or 

Snow 

Amount  of 
Precipita- 
tion 

Mon. 

1 

Tues. 

Wed. 

Thur. 

Fri. 

Mon. 

Tues. 

Wed. 

Thur. 

Fri. 

Mon. 

Tues. 

Wed. 

Thur. 

Fri. 

Mon. 

Tues. 

Wed. 

Thur. 

Fri. 

267 


Date 

Day  of 
Week 

Hour 
of  Day 

Tem- 
pera- 
ture 

Baro- 
metric 
Pressure 

Wind  Direction 

Wind  Velocity 

Kinds  of  Clouds 

Rain  or 

Snow 

Amount  of 
Precipita- 
tion 

Mon. 

Tues. 

Wed. 

Thur. 

Fri. 

Mon. 

Tues. 

Wed. 

Thur. 

Fri. 

Mon. 

Tues. 

Wed. 

Thur. 

Fri. 

Mon. 

Tues. 

Wed. 

Thur 

Fri. 

268 


Date 

Day  ok 
Week 

Hour 
of  Day 

Tem- 
pera- 
ture 

Baro- 
metric 
Pressure 

Wind  Direction 

Wind  Velocity 

Kinds  of  Clouds 

Rain  or 

Snow 

Amount  of 
Precipita- 
tion 

Mon. 

Tues. 

Wed. 

Thur. 

Fri. 

Mon. 

Tues. 

Wed. 
Thur. 

'• 

Fri. 

Mon. 

- 

- 

Tues. 

Wed. 

Thur. 

• 

Fri. 

Mon. 

Tues. 

Wed. 

Thur. 

Fri. 

269 


Date 

Day  of 
Week 

IIOUE 

of  Day 

Tem- 
pera- 
ture 

Baro- 
metric 
Pressure 

Wind  Direction 

Wind  Velocity 

Kinds  of  Clouds 

Rain  oe 

Snow 

Amount  of 
Precipita- 
tion 

Mon. 

Tues. 

Wed. 

* 

Thur. 

Fri. 

Mon. 

Tues. 

Wed. 
Thur. 

Fri. 

Mon. 

Tues. 

Wed. 

Thur. 

Fri. 

Mon. 

Tues. 

Wed. 

Thur 

Fri. 

270 


LXL  —  THE    SEASONAL   TEMPERATURE   RANGE 
Materials.  For  Each  Student.  —  Colored  pencils 

Purpose.  To  study  the  monthly  range  of  temperature  in  different  regions;  to  see  how  it  varies  from 

place  to  place,  and  to  interpret  some  of  the  variations.  Also  to  study  the  daily  range  in  some  of 
these  same  places. 

Making  of  Which  is  the   hottest   month   in  your  locality?     The  coldest 

a  seasonal 

tempera-       month?     If  you  had  twelve  temperature  records,  one  for  every  two 

ture  curve.  ]10urs  jn  ^ne  (jay)  how  would  you  obtain  the  average  or  mean  temperature  for  that  day  ? 

Knowing  the  mean  temperature  for  each  day  in  the  month,  how  would  you  find  the  mean  tem- 
perature for  the  month?     1 

There  follows  a  list  giving  the  mean  temperature  (in  Fahrenheit 

degrees)  for  each  month  of  the  year  at  a  certain  place  in  northern  United  States.  From  this 
data  construct  a  curve  on  the  cross-section  paper  to  show  the  seasonal  change  in  temperature. 
Let  each  vertical  line  represent  a  month,  and  each  horizontal  line  10°. 

Jan.  Feb.  March  April  May  June  July  Aug.  Sept.  Oct.  Nov.  Dec. 
31°        32°  35°  45°  60°  70°         75°         74°         68°         56°        45°        34° 

The  teacher  may  obtain  (from  the  nearest  Weather  Bureau  Station)  the  monthly  mean  temperatures 
for  a  place  near  the  school.  From  this  data  construct  a  seasonal  curve  for  your  locality  over  the  diagram  just 
made,  using  a  different  colored  pencil. 

How   does    the   seasonal    temperature   curve   resemble    the   daily   temperature   curve? 


When  is  the  warmest  period?     The  coldest  period?     

V 

Why  do  these  periods  not  coincide  exactly  with  the  longest  and  the  shortest  days? 


Clearly  state  the  reasons  why  summer  is  the  warmest,  and  winter  the  coldest  period. 

271 


Seasonal  There  follows  a  table  giving  the  monthly  mean  temperatures  (approximate)  for  a  number 

tempera-      0f  places  in  different  parts  of  the  world.     On  the  cross-section  paper  make  a  diagram  to  show 
thUfVeS  ^e  seasoual  temperature  curve  for  each  of  these  places  (all  on  one  diagram).     Let  each  hori- 
parts  of  the  zou^a^  ^ne  stand  for  5°  and  every  second  vertical  line  for  a  month.     Make  room  for  tempera- 
world,  tures  as  high  as  95°  and  as  low  as  45°.     For  each  curve  use  a  differently  colored  pencil,  or 
different  symbols  (such  as  dots  or  dashes). 


Place 

Jan. 

Fjsb. 

March 

April 

Mat 

June 

July 

Aug. 

Sept. 

Oct. 

Nov. 

Dec. 

New  York  City 

37° 

31° 

35° 

52° 

62° 

72° 

75° 

75° 

70° 

56° 

45° 

33° 

Singapore 

80° 

81° 

82° 

82° 

83° 

83° 

83° 

82° 

82° 

81.5° 

81° 

80° 

Arctic,  Lat.  82°, 
Fort  Conger 

-37° 

-43° 

-23° 

-11° 

17° 

32° 

37° 

35° 

15° 

-10° 

-26° 

-30° 

Key  West,  Fla. 

69° 

68° 

72° 

75° 

79° 

81° 

84° 

83° 

83° 

80° 

74° 

69° 

Yuma,  Ariz. 

55° 

62° 

64° 

68° 

73° 

83° 

92° 

90° 

83° 

74° 

61° 

57° 

St.  Vincent,  Minn. 

-5° 

2° 

15° 

35° 

50° 

62° 

66° 

65° 

52° 

40° 

22° 

5° 

Central  Australia 

94° 

92° 

89° 

85° 

75° 

70° 

65° 

60° 

65° 

70° 

78° 

87° 

Central  Atlantic 
at  equator 

79° 

80° 

80.5° 

81° 

80.5° 

80° 

79° 

80° 

80.5° 

81° 

80.5° 

79° 

In  what  one  respect  are  most  of  these  curves  alike  ? 


Why 


Why  does   the  curve  for   Central 


Australia  differ  so  widely  from  the  others  ? 


Which  curve  is  the  flattest  ? 


Why 


272 


Which  region  has  the  coldest  summers  ? 
The  coldest  winters  ?     


What  does  the  difference  between  the  curve  at  St.  Vincent  and  Key  West  or  Singapore 
suggest  as  to  the  influence  of  distance  from  the  sea  ?    1 


Where  do  you  find  the  highest  tempera- 


tures ? 


State  what  you  observe  from  the  study  of  the  diagrams  (a)  as  to  the  influence  of  latitude  on 
the  seasonal  temperature  curve ;    


(&)  as  to  the  influence  of  distance  from  the  sea. 


• 


Daily 
changes  in 
tempera- 
ture in 
different 
eg  ions. 


The    temperature 

falls  on  the  average  of  1°  for  every  300  feet  of  altitude.     On  the  diagram  (just  drawn),  dot  in 
a  curve  to  show  a  theoretical  seasonal  curve  at  an  elevation  of  3000  feet  above  New  York 

City. 

On  the  cross-section  paper  plot  the  data  in  the  following  table  to  show  the  daily  changes 
in  temperature  at  some  of  the  places  for  which  the  seasonal  curves  have  just  been  drawn. 
Use  colored  pencils ;  use  dots  to  represent  the  winter  days  and  continuous  lines  for  summer 
days.  Let  every  other  vertical  line  represent  3  hours  of  the  day,  and  each  horizontal  line  5° 
of  temperature.     Make  room  for  temperatures  as  high  as  95°  and  as  low  as  —  30°.  ■ 


273 


Place 

Mid- 
night 

3   A.M. 

6    A.M. 

9    A.M. 

Noon 

3    P.M. 

6   P.M. 

9   P.M. 

Mid- 
night 

New  York  City.     Summer 

62° 

58° 

59° 

65° 

72° 

79° 

78° 

72° 

60° 

New  York  City.     Winter 

10° 

8° 

6° 

12° 

24° 

30° 

25° 

18° 

10° 

Arctic.     Winter 

-10° 

—  12° 

-14° 

-15° 

-17° 

-19° 

-22° 

-24° 

-26° 

Key  West,  Fla.     Summer 

80° 

77° 

80° 

84° 

89° 

90° 

87° 

82° 

79° 

Key  West,  Fla.     Winter 

69° 

65° 

69° 

73° 

78° 

79° 

75° 

71° 

69° 

St.  Vincent,  Minn.     Summer 

60° 

55° 

59° 

69° 

78° 

85° 

78° 

69° 

60° 

St.  Vincent,  Minn.     Winter 

—  22° 

—27° 

-29° 

-19° 

-12° 

-11° 

-13° 

-20° 

-23° 

Central  Atlantic  at  Equator. 
Summer 

79.8° 

79.5° 

79.3° 

80° 

80.5° 

81° 

80.5° 

80° 

79.8° 

Central  Atlantic  at  Equator. 
Winter 

79.9° 

79.6° 

79.3° 

80° 

80.5° 

81° 

80.6° 

80.1° 

79.9° 

In  what  respect  are  all  but  one  of  these  daily  curves  alike  ? 


. Which  one   does  not  show 

the    midday    rise?     Why    does     it     not? 


Which  curve  shows  the  greatest  change  between  day  and  night  ? 
Explain.     


Wrhich  the  least  ? 


Explain. 


Where    is    it    coldest?     Where    warmest? 


274 


What  evidence  do  you  find  of  (a)  influence 

of  ocean?     


(b)  of  influence  of  distance  from  sea  ? 


(c)  of  influence  of  latitude  ? 


275 


i 


Materials. 


Purpose. 


Note. 


Water 
vapor  in 
the  air. 


Experi- 
ments to 
illustrate 
variation  in 
the  rate  of 
evapora- 
tion. 


LXII.  —  MOISTURE   IN   THE   AIR 

For  Each  Student.  —  Two  small  pieces  of  cheese  cloth,  two  or  three  inches  square. 
For  General  Class  Use.  —  A  fruit  jar.     (A  small  vial  of  alcohol  or  ether.)     A  small  piece  of 
muslin.     Two  thermometers. 

To  understand  the  four  different  conditions  which  affect  the  rate  of  evaporation  ;  the  meaning 
of  relative  and  absolute  humidity ;  and  the  use  of  the  table  for  determining  the  relative  humidity, 
on  the  basis  of  observations  of  temperature  with  the  dry  and  wet  bidb  thermometers. 

Note  :  —  To  save  time  the  teacher  will  probably  direct  that  two  or  more  of  these  experiments  be  carried 
on  at  the  same  time. 

After  it  has  stopped  raining  the  sidewalks  soon  become  dry.     What  has  become  of  the 

water  ? 

What  term  is  applied  to  the  change  from  water  to  water  vapor  ?     

Is  the  water  vapor  a  liquid  or  a  gas  ?     Is  it  visible  or  invis- 
ible?      _ All  over  the  earth  water  is  evaporating,  and  the  water  vapor 

is  rising  into  the  air ;  but  the  rate  at  which  evaporation  takes  place  varies  greatly  under  dif- 
ferent conditions.     The  following  experiments  are  intended  to  illustrate  this  fact. 

Wet  both  the  pieces  of  cheese  cloth.  Put  one  on  the  radiator,  or  in  the  sun,  or  in  some 
other  warm  place.     Put  the  other  on  your  desk,  and  not  in  the  sun.     Which  piece  of  cloth 

becomes  dry  first  ?     From  this  experiment 

what  do  you  conclude  as  to  the  rate  of  evaporation  at  different  temperatures?     


Would   evaporation   therefore  be   more  rapid   in   the   frigid   zone   or   in   the   torrid   zone  ? 

In  summer  or  in  winter?     

Again  wet  each  piece  of  cloth,  wringing  out  the  surplus  water.     Pin  one  of  the  pieces  on 
each  end  of  your  desk.     With  a  book  or  piece  of   paper,  fan  one  of   the  pieces  of   cloth. 

Which  dries  the  more  quickly?     What  do 

you  conclude  from  the  results  of  this  experiment  as  to  the  rate  of  evaporation  where  the  wind 

is  blowing,  as  compared  to  the  rate  where  it  is  calm  ?     

Would  evaporation,  therefore,  be  more  rapid 

277 


on  a  windy  day  or  on  a  day  when  there  is  no  wind  ?      

Would  it  be  more  rapid  in  the  trade  wind  belt,  or  in  the  belt  of  calms?     

Once  more  wetting  the  two  pieces  of  cloth,  spread  one  out  on  the  desk  and  make  a  small 

roll  of  the  other.    Which  dries  the  more  quickly? 

What  do  you  conclude  from  this  experiment  as  to  the  relation  between  the  amount  of  evapo- 
ration and  the  amount  of  surface  exposed? 


1 Would  there,  therefore,  be  more  water  vapor 

rising  from  a  large  body  of  water  (such  as  the  ocean)  or  from  a  small  body  (such  as  a  pond)  ? 

Which  would  probably  have  more  vapor, 

winds  from  the  land  or  winds  from  the  ocean?    

While  these  experiments  were  being  carried  on,  the  teacher  has  placed  a  small  amount  of 
water  in*  the  bottom  of  a  fruit  jar  and,  putting  on  the  cover,  has  set  it  in  a  warm  place. 
Evaporation  has  caused  much  water  vapor  to  rise  into  the  air  in  the  jar,  and  this  air  is  there- 
fore very  damp.  Now  suspend  a  piece  of  wet  cloth  (by  a  string)  in  the  jar,  and  put  back  the 
cover.     At  the  same  time  spread  out  another  piece  of  wet  cloth  on  the  desk.     When  the  cloth 

on  the  desk  is  dry,  take  out  the  piece  of  cloth  from  the  jar.     Is  it  dry  ?     

What  do  you  conclude  as  to  the  rate  of  evaporation  in  dry  air  as  compared  to  that  in  damp 


air  r 


Would  evaporation,  therefore,  be  more  rapid  on  a  damp  day  or  on  a  dry  day 
In  a  desert  or  in  a  humid  region?     


Meaning  of  A  quart  dish  half  full  of  water  has  |,  or  50%,  as  much  water  as  it  can  hold.     This  per- 

absolute        centage  represents  the  relative  amount  of  water  in  the  glass  compared  with  what  the  dish 
and  relative 

Umi  1  y*      might  hold.     What  would  be  the  percentage  if  the  dish  were  full?     . 


What  if  §  full  ? 


You  could  state  the  amount  of  water  in  the  dish  in  two  ways :  that  is,  you  could  say,  when 
the  dish  was  half  full,  that  the  absolute  amount  was  a  pint ;  or,  you  could  say  that  the  amount 
relative  to  what  the  dish  might  hold  was  50%. 

It  is  important  sometimes  to  speak  of  the  absolute  and  relative  amounts  of  vapor  in  the 
air.     If  you  had  a  given  quantity  of  perfectly  dry  air,  and  let  one  pint  of  water  evaporate 

into  it,  what  would  be  the  absolute  amount  of  vapor  in  the  air  ?     '_'__ 

This  would  be  called  its  absolute  humidity.     To  determine  the  relative 
278 


UM1VERSU* 

OF 

humidity  you  would  need  first  to  know  how  much  vapor  could  possibly  pass  into  that  quan- 
tity of  air.     Suppose  the  amount  of  water  that  this  quantity  of  air  could  hold  was  4  pints ; 

what  would  be  the  relative  humidity  when  its  absolute  humidity  was  1  pint?     

What  would  be  its  relative  humidity  if  there  were  2  pints 

in  it?      What  if  there  were  4  pints  in  it? 

Could  it  then  take  any  more  water  vapor? 

What,  then,  is  meant  by  saturated  air?     

Was  the  air  saturated  when  the  water 

was  being  evaporated  from  the  pieces  of  cloth  on  the  desk  ?     If  it  had  been, 

could  there  have  been  any  evaporation  ?     

Determin-  Evaporation  is  a  cooling  process,  because  in  evaporation  heat  must  be  used.     This  can  be  proved  by 

ing  relative    placing  a  drop  of  ether  or  alcohol  on  the  back  of  the  hand.     As  it  evaporates  it  takes  some  heat  from  the 

humidity.       hand  and  therefore  feels  cool.     Take  two  thermometers  and  hang  them  side  by  side.     Tie  (with  thread)  a 

small  piece  of  muslin  around  the  bulb  of  one,  with  one  end  of  the  muslin  hanging  down  like  a  wick.     Read 

the  two  thermometers.     Now  saturate  the  muslin  with  alcohol  and  watch  the  mercury  of  this  thermometer. 

Why  does  this  thermometer  register  a  lower  temperature  than  the  other  ?    

See  if  water  has  the  same  effect 

as  alcohol,  saturating  the  muslin  and  letting  the  wick  end  rest  in  a  glass  of  water  ;  but,  since  water  does  not 
evaporate  as  fast  as  alcohol,  fan  the  muslin  to  make  the  water  evaporate  more  rapidly. 

It  is  possible  to  determine  the  relative  humidity  of  the  air  by  using  two  such  thermometers — a  dry  bulb 
and  a  wet  bulb  thermometer.  The  principle  is  that  the  evaporation  lowers  the  temperature.  The  tempera- 
ture is  lowered  more  if  evaporation  is  rapid  than  if  slow.     Which  is  dryest,  air  with  low  relative  humidity,  or 

air  with  high  relative  humidity?    In  which  will  evapo- 
ration be  more  rapid,  air  with  high  or  low  relative  humidity  ?    

From  this  do  you  conclude  that  the  difference  in  temperature  as  shown  by  the  dry  and  wet  bulb  thermome- 
ters would  be  greater  when  the  relative  humidity  is  high,  or  when  low  ?     


Following  is  a  table  which  can  be  used  to  determine  the  relative  humidity.  First  find  the  difference  in 
temperature  of  the  dry  and  wet  bulb  thermometers.  Suppose  it  to  be  3°.  Find  the  number  3  (the  third  figure 
from  the  left)  at  the  top  of  the  table.  In  the  left-hand  column  of  the  table  find  the  number  that  corresponds 
with  the  temperature  recorded  by  the  dry  bulb  thermometer,  which  we  will  assume  to  be  78°.  Now  follow 
this  to  the  right  until  you  come  to  the  number  in  the  column  under  the  3.  That  number  is  87,  and  this  is  the 
relative  humidity.    That  is,  the  relative  humidity  is  87  %. 


279 


Below  is  a  table  showing  observations  made,  and  the  relative  humidity  indicated  by  them,  as  deduced 
from  the  table. 


Date 

Dry  Bulb 

Wet  Bulb 

Difference  in  Reading 

Relative  Humidity 

Jan.  1 

80° 

78° 

2° 

92% 

Jan.  2 

82° 

78° 

4° 

84% 

Jan.  3                              74° 

67° 

7° 

70% 

Verify  these  data  by  use  of  the  table  for  determining  relative  humidity.  Make  observations  with  the 
dry  and  wet  bulb  thermometers,  both  in  the  schoolroom  and  out  of  doors,  and,  by  reference  to  the  table,  find 
the  relative  humidity.     Set  down  the  results,  below,  in  a  table  similar  to  that  just  given. 


280 


Table  for  determining  Relative  Humidity 


# 


Tempera- 

ture of  I)r 
Bulb  Tiiek 

5  i 

2 

3 

4 

5 

6 

7 

8 

9 

10 

n 

12 

13 

14 

15 

16 

17 

18 

19 

20 

21 

22 

23 

24 

25 

MOMETER 

20°  .  .  . 

85 

70 

56 

41 

27 

13 

22°  .  .  . 

86 

72 

58 

45 

32 

19 

6 

24°  .  .  . 

87 

74 

61 

48 

36 

24 

11 

26°  .  .  . 

88 

75 

63 

51 

40 

28 

17 

6 

28°  .  .  . 

88 

77 

65 

54 

43 

33 

22 

11 

1 

30°  .  .  . 

89 

78 

67 

57 

47 

36 

26 

17 

7 

32°  .  .  . 

90 

79 

69 

59 

50 

40 

31 

21 

12 

3 

34°  .  .  . 

91 

81 

72 

62 

53 

44 

35 

26 

17 

9 

36°  .  .  . 

91 

82 

73 

66 

56 

47 

38 

30 

22 

14 

6 

38°  .  .  . 

92 

83 

75 

67 

58 

50 

42 

34 

26 

18 

11 

3 

40°  .  .  . 

92 

84 

76 

68 

60 

53 

45 

38 

30 

22 

16 

8 

1 

42°  .  .  . 

92 

84 

77 

69 

62 

55 

48 

40 

34 

27 

20 

13 

6 

44°  .  .  . 

92 

85 

78 

70 

63 

57 

50 

43 

37 

30 

24 

17 

11 

5 

46°  .  .  . 

93 

85 

79 

72 

65 

58 

52 

46 

39 

33 

27 

21 

15 

9 

3 

48°  .  .  . 

93 

86 

79 

73 

66 

60 

53 

48 

42 

36 

30 

24 

19 

13 

7 

2 

50°  .  .  . 

93 

87 

80 

74 

67 

61 

55 

50 

44 

38 

33 

27 

22 

16 

11 

6 

1 

52°  .  .  . 

94 

87 

81 

75 

69 

63 

57 

51 

46 

40 

35 

30 

24 

20 

15 

10 

5 

54°  .  .  . 

94 

88 

82 

76 

70 

64 

59 

53 

48 

43 

38 

32 

28 

23 

18 

13 

8 

4 

56°  .  .  . 

91 

88 

82 

77 

71 

65 

60 

55 

50 

44 

40 

35 

30 

25 

21 

16 

12 

8 

3 

58°  .  .  . 

94 

89 

83 

78 

72 

67 

61 

56 

51 

46 

42 

37 

33 

28 

24 

19 

15 

11 

7 

2 

60°  .  .  . 

94 

89 

84 

78 

73 

68 

63 

58 

53 

48 

44 

39 

34 

30 

26 

22 

18 

14 

10 

6 

2 

62°  .  .  . 

95 

89 

84 

79 

74 

69 

64 

59 

54 

50 

45 

41 

37 

32 

28 

24 

20 

16 

13 

9 

5 

1 

64°  .  .  . 

95 

90 

85 

79 

74 

70 

65 

60 

56 

51 

47 

43 

38 

34 

30 

27 

23 

19 

15 

12 

8 

5 

1 

66°  .  .  . 

95 

90 

85 

80 

75 

71 

66 

61 

57 

53 

49 

45 

40 

36 

32 

29 

25 

22 

18 

14 

11 

8 

4 

1 

68°  .  .  . 

95 

90 

85 

81 

76 

71 

67 

63 

58 

54 

50 

46 

42 

38 

34 

31 

27 

24 

20 

17 

14 

10 

7 

4 

1 

70°  .  .  . 

95 

90 

86 

81 

77 

72 

68 

64 

60 

55 

52 

48 

44 

40 

36 

33 

29 

26 

23 

19 

16 

13 

10 

7 

4 

72°  .  .  . 

95 

91 

86 

82 

77 

73 

69 

65 

61 

57 

53 

49 

45 

42 

38 

35 

31 

28 

24 

22 

18 

15 

12 

9 

6 

74°  .  .  . 

95 

91 

86 

82 

78 

74 

70 

66 

62 

58 

54 

50 

47 

43 

40 

36 

33 

30 

26 

23 

20 

18 

15 

12 

9 

76°  .  .  . 

95 

91 

87 

82 

78 

74 

70 

66 

63 

59 

55 

52 

48 

45 

41 

38 

35 

31 

28 

25 

22 

20 

17 

14 

11 

78°  .  .  . 

96 

91 

87 

83 

79 

75 

71 

67 

63 

60 

56 

53 

49 

46 

43 

39 

36 

33 

30 

27 

24 

21 

19 

16 

13 

80°  .  .  . 

96 

92 

87 

83 

79 

75 

72 

68 

64 

61 

57 

54 

51 

47 

44 

41 

38 

35 

32 

29 

26 

23 

20 

18 

15 

82°  .  .  . 

96 

92 

88 

84 

80 

76 

72 

69 

65 

62 

58 

55 

52 

48 

45 

42 

39 

36 

33 

31 

28 

25 

22 

20 

17 

84°  .  .  . 

96 

92 

88 

84 

80 

77 

73 

69 

66 

63 

59 

56 

53 

49 

46 

44 

41 

38 

35 

32 

29 

27 

24 

22 

19 

86°  .  .  . 

96 

92 

88 

84 

81 

77 

73 

70 

67 

63 

60 

57 

54 

51 

48 

45 

42 

39 

36 

34 

31 

29 

26 

23 

21 

88°  .  .  . 

96 

92 

88 

85 

81 

77 

74 

71 

67 

64 

61 

58 

55 

52 

49 

46 

43 

40 

38 

35 

32 

30 

27 

25 

22 

90°  .  .  . 

96 

92 

88 

85 

81 

78 

75 

71 

68 

65 

62 

59 

56 

53 

50 

47 

44 

41 

39 

36 

34 

32 

29 

26 

24 

281 


LXIII.  —  CONDENSATION  OF  WATER  VAPOR 

Materials.  For  Each  Student.  —  A  drinking  glass.     Water.     Either  snow  or  small  pieces  of  ice. 

Purpose.  To  understand  the  causes  leading  to  the  condensation  of  water  vapor,  and  the  consequent 

formation  of  dew,  frost,  fog,  clouds,  rain,  and  snow. 

Meaning  of  In  which  can  there  be  most  vapor,  warm  air  or  cold  air? 

saturation     if  the  relative  humidity  of  the  air  is  90  %  when  the  temperature  is  70°,  would  the  temperature 
and  dew 

poin  '  need  to  be  raised  or  lowered  to  bring  the  relative  humidity  to  100%  ? 

If  the  temperature  continued  to  change  in  the  same  direction  until 

after  the  point  of  saturation  was  reached,  what  would  happen  ?      _> 

; What  reason  can  you  give 

for  calling  the  point  of  saturation  (relative  humidity  100%)  the  dew  point  f     


Formation  Breathe  against  a  cold  object,  like  a  window  pane.     What  happens  ? 

of  dew. 

Explain  why  the  vapor  was  condensed?     ._ 


Fill  the  drinking 

glass  two  thirds  full  of  water  and  ice  (or  snow)  and  stir  the  mixture,  being  careful  not  to  wet 
the  outside  of  the  glass.     Explain  why  water  begins  to  appear  on  the  outside  of  the  glass. 


In  the  evening,  when  the  ground  cools  by  radiation,  dew  often  forms.     Explain  the  cause 
of  the  formation  of  dew. 


283 


Would  dew  form  most  quickly  when  the  relative  humidity  is  high, 

or  low?     When  would  no  dew  form? 

What  forms  if  the  dew  point  is  below  the  freezing  point? 


Determina-  Again  place  water  and  snow  (or  ice)  in  the  drinking  glass  and  stir  the  mixture  carefully  with  the  ther- 

tion  of  dew    mometer.     Note  when  vapor  first  begins  to  condense  on  the  outside  of  the  glass  and  then  read  the  thermometer. 
point.  The  temperature  of  that  reading  is  the  dew  point  for  the  air  in  the  room.     Determine  the  dew  point  by  this 


method. 


Formation  When  you  breathe  into  the  air  of  a  cold  winter  day,  you  can  "see  your  breath."     What  is 

of  fog. 


it  that  you  see  ?      

Explain  what  has  happened. 


What  must  happen  when  warm,  damp 

winds  blow  over  a  cold  surface?     

On  this  basis,  explain  why  it  is  that  the  cold  Labrador 

current  is  such  a  foggy  part  of  the  ocean.      ■_ 


Why  is  it  that  winds  often  cause  fog  on  mountains  ? 


Formation  Air  that  rises  above  the  earth's  surface  expands ;  and  when  air  expands  it  grows  cooler. 

of  clouds.      What  then  must  result  if  damp  air  (or  air  with  high  relative  humidity)  rises  to  a  considerable 


height  ? 


If  you  could  see  a  fog  from  either  above  or  below,  it  would  look  like  a  cloud. 

284 


Explain  why  clouds  form  every  day  in  the  warm,  humid  belt  of  calms. 


* 


Explain  why   clouds 


appear  on  warm,  humid  summer  days. 


Observa- 
tion of 
clouds. 


In  the  Text-book  (p.  248)  you  will  find  the  names  of  the  principal  forms  of  clouds.     What 

form  have  the  clouds  to-day  ? Keep  a  record 

of  the  clouds  for  a  week,  giving  their  name,  form,  and  a  brief  description,  in  the  following 

table.     Erom  which  kind  of  cloud  does  rain  or  snow  fall?     


Formation 
of  rain. 


Causes  for 
differences 
in  rainfall. 


^A  differences 


Day  op  Week 

Name  op  Cloud 

Description  of  Clouds 

Monday 

Tuesday 

Wednesday 

Thursday 

Friday 

If  condensation  continues,  will  the  clouds  grow  larger  or  smaller?     

What  does  the  fact  that  the  fog  particles  float  in  air  currents  indicate 

as  to  their  size?  When  condensation  con- 
tinues, what  must  be  the  effect  on  the  size  of  the  particle?     

What  must  thenhappen?     

Under    what   conditions    is    snow    formed 

instead  of  rain? 

In  the  belt  of  calms  the  air  is  rising.     Would  this  be  a  rainy  or  a  dry  region  ?     


State  your  reasons  for  this  conclusion. 

285 


In  the 

horse  latitude  belt  the  air  is  descending.     Would  this  be  a  rainy  or  a  dry  region  ?     

State  your  reasons  for  this  conclusion.      


Where  winds 

blow  from  the  ocean  against  rising  land,  would  there  be  much  or  little  rain  ? 
State  your  reasons  for  this  conclusion.     


Where  winds  blow  from  the  land  to  the  ocean,  what  condition  of  rainfall  would  there  be  ? 
. State  your  reasons  for  this  conclusion.     


286 


Materials. 


Purpose. 


Making  an 
isothermal 
chart. 


LXIV.  —  ISOTHERMAL   CHARTS   OF   UNITED   STATES 

For  Each  Student.  —  Colored  pencils. 

To  make  and  understand  an  isothermal  chart;  to  study  and  interpret  a  summer  and  winter 
isothermal  chart  of  the  United  States;  and  to  bring  out  the  fact  that  temperature  conditions  are  of 
great  and  fundamental  importance  to  vegetation. 

On  the  accompanying  map  (Fig.  28)  are  marked  the  temperatures  at  a  number  of  localities 
in  the  United  States  at  8  a.m.  on  a  winter's  day.  With  this  data  draw  in  (as  directed  below) 
isothermal  lines  so  as  to  connect  places  having  the  same  temperature.  Your  map  then  becomes 
an  isothermal  chart.  It  will  be  sufficient  to  draw  an  isothermal  line  for  every  ten  degrees ;  e.g 
for  0°,  10°,  20°,  etc. 

In  making  the  map  start  with  the  isothermal  line  for  50°.  Since  the  temperature  at  New 
Orleans  was  50°,  it  is  evident  that  the  line  will  have  to  pass  through  that  city.     Will  it  run 


through  Mobile?     Macon? 


Augusta  ? 


Will  it  then  continue  nearer  Ealeigh  (48°)  or  Wilmington,  N.C.  (56°)  ? 


Draw   the  line  at  what  you  think  is  the  proper  distance  from 

Ealeigh.     At  Norfolk  the  temperature  was  54°.     Will  the  50°  isotherm  pass  on  the  cold  side 

(north)  or  on  the  warm  side  (south)  of  Norfolk? 

Continue  the  50°  isothermal  line  southeastward  from  New  Orleans.     On  which  side  of  Galves- 
ton does  it  extend?     On  which  side  of  Corpus 

Christi,  Tex.  ?    ._'_ 

Now  draw  the  60°  and  70°  isothermal  lines  across  the  Florida  peninsula.  Then  draw  in 
the  other  isotherms  down  to  20°  below  zero.  Shade  (with  blue  pencil)  the  part  of  the  map 
with  a  temperature  below  30° ;  this  is  (approximately)  the  area  of  the  country  where  the  tem- 
perature is  below  freezing  point  on  that  day.     


Questions 
on  the 
isothermal 
chart. 


Where  is  the  coldest  area  ? 


Why  should  it  be  coldest  there  ? 


28T 


Why    does    the  30° 

isotherm  extend  farther  south  in  the  interior  than  on  the  east  and  west  coasts  ?     


Why  should  it  be  farther  north  on  the  west  than  on  the  east  coast  ? 


Study  of 
isothermal 
charts  of 
United 
States  for 
January 
and  July. 


Fill   out   this  sentence: 


This  isothermal  chart  shows  that  in  winter  the  temperature from  south 

to  north ;  and  it  also  shows  that  the  temperature from    seacoast  to 

interior. 

The  isothermal  chart  that  you  have  just  made  represents  the  conditions  in  the  country  at 
8  o'clock  on  a  single  day.  If  all  the  temperature  records  at  each  locality  for  a  month  were 
averaged  together,  an  isothermal  chart  could  be  made  for  that  month.  This  is  what  has  been 
done  in  the  two  charts  (Figs.  29  and  30),  one  for  the  month  of  January,  the  other  for  July. 

With  the  colored  pencils  shade  in  the  following  areas :  (a)  those  with  temperatures  below 
0°;  (b)  those  with  temperatures  between  0°and  30°;  (c)  those  with  temperatures  between  30° 
and  50° ;  (d)  those  with  temperatures  between  50°  and  70° ;  (e)  those  above  70°. 

What  is  the  general  direction  that  the  isotherms  follow  ?     

Where   is    there    the   greatest   departure    from    this    direction? 


What  is  the  explanation  of  this  ? 


On  which  coast,  the  Atlantic  or  the  Pacific,  is  there  the 

greatest  difference  in  temperature  in  going  from  north  to  south?     

How  much  difference  in  temperature  is  there  between  the  north  and 

south  ends  of  each  coast  in  summer  ?     


In  winter  ? 


288 


289 


130___\?Al£o0  120° W  110° 1062 IS^l 95°  90°  8a"  80"         75 70° 65° 00° 


108°  Longitude      100°       West  95°        from  90°    Greemrieh       85°        70 


Fig.  29.  —  Isothermal  Chart  of  United  States  for  January. 


125°  120°  116°  110°  105°  100°  95°  90°  85°  80 


70°  66° 


105°    Longitude      100°        Wert  95°         from  90°     Greenwioh      85 


Fig.  30.  —  Isothermal  Chart  of  United  States  for  July. 

291 


Why  is  there  a  marked  difference  of  temperature  range 


on  the  two  coasts  ? 


Which  of  these  two  monthly  charts  does  Figure  28  most  resemble?    

Do  Figures  28,  29,  and  30  show  the  same  general  features?     

In  what  part  of  the  country  is  there  the  greatest  difference  in  tem- 
perature between  summer  and  winter?     


Why  is  this  so  ? 


ence?    

Explain  this  also. 


Where  is  there  the  least  differ- 


Which  is  the  most  southern  point  in  the  country  ? 
Is  it  the  warmest  place  in  the  country   in  summer  ? 


Account    for   this. 


What  is  the  warmest  place  in  the  country  in  winter  ? 
Which  is  the  most  northern  point  in  the  country  ?  ._ 
Is  it  also  the  coldest  part  of  the  country  in  winter  ? 


Explain. 


293 


LXV.  —  THE   RELATION  OF   WINDS   TO  ATMOSPHERIC   PRESSURE 

Purpose.  To  show  that  winds  are  caused  by  the  flowing  of  air  from  regions  of  high  pressure  to  regions 

of  lower  pressure. 

Movement  The  air  near  a  hot  stove,  a  radiator,  or  lamp,  is  warmed.     Hold  a  light,  downy  feather 

of  light  and  near  one  of  these  and  then  release  it.     What  is  the  movement  of  the  current  of  air  near  this 
heavy  air. 

heated  object? Why  is  this  so?     


Could 


the  air  rise  against  gravity  unless  something  were  pushing  it  up  ?      When  the 

warm  air  near  a  stove  is  rising,  what  is  the  movement  of  the  cooler,  heavier  air  in  other  parts 


of  the  room  ? 


What  effect  has  this  movement  on  the  warm,  lighter  air? 


-  m- 

1 

W 

rl 

■<p- — 

•  A 

J 

3 


Fig.  31.  —  Diagram  for  showing  Circulation  of  Air  in  Room  heated  by  a  Stove. 

295 


In  the  diagram 

(Fig.  31)  draw  arrows  to  show  the  circulation  of  the  air  in  a  room  warmed  by  a  stove.     Fill 
in  the  following  sentence,  putting  the  words  "  lighter  "  or  "  heavier  "  in  their  proper  places. 

Warm  air  is than  cool  air ;  the  cool air 

settles  and  forces  up  the warm  air.     This  causes  the  cool 

air  to  flow  toward  places  of  warm air. 

Is  it  true  on  the  earth,  as  well  as  in  a  room,  that  heavy  air  will  flow  toward  regions  of 

light  air  and  force  the  light  air  to  rise  ?     What  is  the  instrument  that  is  used 

to  measure  the  weight  or  pressure  of  the  air?     Recalling  your  study 

of  the  barometer,  which,  heavy  or  light  air,  makes  the  mercury  rise  higher  in  the  instrument? 

At  about  what  height  does  the  mercury  stand 

in  the  barometer  tube  ?     Does  a  reading  of  the 

barometer  of  29.8  inches  mean  heavier  or  lighter  air  than  a  reading  of  30.2  inches? 

Which  of  these  two  would  be  called  high  pressure? 

Which  low  pressure  ?     

Figure  32  is  a  map  of  the  United  States  showing  the  pressure  of  trie  air  for  a  certain  day 
in  winter.  The  lines  are  called  isobars  (meaning  equal  weight),  and  each  line  passes  through 
places  having  the  same  air  pressure,  or  weight.  The  figures  on  each  line  show  the  pressure  in 
inches  of  mercury  in  the  barometer  on  this  day.     Find  the  place  with  the  lowest  pressure  and 

write  in  the  words  "low  pressure."     Is  this  a  region  of  light  air  or  of  heavy  air? 

On  the  map  mark  in  the  words  "  high  pressure  "  where 

they  belong. 

From  the  center  of  which  of  these  areas  will  the  air  flow  outward?     ,__ 

What  would  you  call  this  flowing  of  the  air?     

Toward  the  center  of  which  of  the  areas  will  the  wind  blow  ?     

With  arrows  mark  in  the  winds  as  you  think  they  would  go  with 

such  a  condition  of  pressure  as  shown  on  this  map. 

Water  running  down  a  slope  is  often  said  to  flow  down  grade.  The  winds  shown  on  your 
map  are  not  flowing  down  a  slope,  but  the  air  is  flowing  from  a  region  of  high  barometric  pres- 
sure to  one  of  low  barometric  pressure.     What  reason  can  you  give  for  calling  the  difference 

in  pressure  between  two  places  a  barometric  gradient?     


296 


297 


Is  the  barometric  gradient  steepest 

where  the  isobars  are  close  together  or  far  apart?     

Where  is  it  gentlest?     On  what  kind 

of  a  grade  does  water  flow  most  swiftly?     On 

what  kind  of  a  barometric  gradient  will  air  flow  most  swiftly  ?       

. ;     On  your  map  mark  places  where  the  air  must  be  moving  swiftly.     Would 

these  regions   have  strong  or   light  winds?      

What  would  be  the  case  where  the  barometric  gradient  is  gentle?      

On  Figure  33  the  arrows  represent  winds  observed  on  a  certain  day  in  a  part  of  the  United 
States.  On  this  map  sketch  in  a  number  of  isobars  to  show  the  location  of  the  area  of  low 
pressure  and  the  area  of  high  pressure. 


Fig.  33.  —  Map  to  show  Wind  Directions  observed  on  a  Certain  Day  in  Part  of  the  United  States. 

299 


# 


Materials. 
Purpose. 


Making  a 

weather 

map. 


Observa- 
tion of  the 
weather 
map. 


LXVL—  THE  WEATHER   MAP 

Colored  pencils. 

To  understand  the  meaning  of  the  symbols  on  a  weather  map  ;  to  appreciate  the  method  of  con- 
structing such  a  map;  and  to  study  the  relations  between  air  ])ressure  and  weather,  under  cyclonic 
and  anticy clonic  conditions. 

On  the  map  of  the  United  States  (Fig.  34)  are  data  from  observations  made  by  the  United 
States  Weather  Bureau  at  8  a.m.  on  a  winter's  day.  At  this  hour  the  observers  at  each  of  the 
places  marked  on  the  map  made  observations  of  their  thermometers,  barometers,  etc.,  and  tele- 
graphed the  results  to  Washington.  There  a  weather  map  was  made  to  show  the  weather  con- 
ditions over  the  entire  country  at  that  hour.  The  data  that  were  telegraphed  to  Washington 
are  printed  on  the  map.     You  are  to  construct  the  weather  map. 

First  draw  the  isothermal  lines  (using  a  red  pencil)  as  directed  on  page  289.  Next  draw  in 
the  isobars,  using  a  blue  pencil.  To  do  this,  follow  the  same  method  as  in  drawing  the  iso- 
thermal lines,  showing  differences  for  each  tenth  of  an  inch  by  a  separate  isobar.  Draw 
each  of  the  isobars  through  places  having  the  same  barometric  pressure ;  or  on  the  proper  side 
of  those  places  where  the  pressure  was  not  exactly  a  tenth  of  an  inch.  For  instance,  the  isobar 
would  be  drawn  through  a  place  having  29.9  inches ;  but  it  must  go  to  one  side  of  a  place 
having  a  reading  of  29.93,  or  of  a  place  having  a  reading  of  29.89.  Having  completed  the  isobars, 
mark  the  word  High  in  the  place  where  the  lines  inclose  an  area  of  high  pressure ;  and  mark 
the  word  Low  in  the  place  where  the  lines  inclose  an  area  of  low  pressure. 

With  black  pencil  or  ink,  draw  arrows  to  show  the  wind  direction  at  each  place,  remem- 
bering that  the  letters  N.W.,  N.,  etc.,  refer  to  the  compass  directions  from  which  the  winds 
blow.  Place  the  point  of  the  arrow  on  the  end  toward  which  the  wind  is  blowing.  Finally, 
color  (with  green  pencil)  the  area  where  rain  (r)  or  snow  (s)  are  falling,  making  the  snow 
area  a  heavier  green  than  the  rain.  In  this  shading  you  can  color  in  the  area  between  places 
that  have  the  same  letters. 

Is  it  colder  within  the  area  of  the  high  or  of  the  low  pressure?     

In  which  of  the  two  areas  is  there  clear  weather  ?     

In  which  is  there  rain  or  snow  ?     


In  what  part  of  the  low-pressure  area  is  rain  falling  ? 


..    In  what  part 


snow? 


0 


Using  the  scale  of  miles  (printed  on  the  map),  measure  the  distance  from  east  to 


west  in  which  there  is  precipitation.     Measure  the  diameter  of  the 

301 


area  of  precipitation  along  a  north-south  line.      Do  the  winds  blow 

toward  or  away  from  the  area  of  high  pressure  ?     

Do  they  blow  toward  or  away  from  the  area  of  low  pressure?     


Interpreta-  If  winds  blow  from  all  sides  toward  a  center,  what  must  become  of  the  air  as  it  flows 

tion  of  the 

weather        toward  the  center  ?     If  the  relative  humidity 

map. 


of  the  air  is  high,  what  must  happen  as  it  rises  ? 


Apply  this  in  explanation  of  the  large 

area  in  which  there  is  precipitation  around  the  Low.     •_ 


Where  does  the  air  obtain  its  vapor? 


What  bearing  has  this  on  the  fact  that  there  is  a  larger  area  of  precipitation  on  the  east  and 
south  sides  of  the  Low  than  on  the  north  and  west?     


Why  is  it  warmer  on  the  south  and 

east  sides  of  the  low-pressure  area  than  on  the  north  and  west  sides  ?     


What  bearing  has  this 

on  the  distribution  of  rain  and  snow  in  the  area  of  precipitation  ?      


302 


303 


If  the  winds  blow  outward  from  an  area  of  high  pressure,  where  does  the  air  come  from  ? 

Is  air  above  the  earth  warmer  or  colder  than 

that  at  the  surface?  (Text-book,  p.  240.)     How  does  this  help  to 

explain  the  temperature  within  the  high-pressure  area? 


Air  settling  from  above  the  surface 

grows  warmer;  does  it  then  cause  clear  or  cloudy  weather  ?  

Apply  this  in  explanation  of  the  conditions  in  the  high-pressure  area. 


Making  a  Figure  35  gives  data  for  the  weather  map  at  8  a.m.  on  the  next  day  to  the  one  just  studied, 

weather  these  data  having  been  obtained  by  the  Weather  Bureau  observers,  as  before.     On  this  map 

map  for  the  (jraw  {n  (&$  on  the  previous  map)  the  isotherms,  isobars,  and  wind  directions ;  color  in  the  areas 

next  day.  Q£  ra-n  an(^  snow .  an(j  mark  the  areas  of  high  and  low  pressure. 

Compari-  In  which  direction  has  the  low-pressure  area  moved  in  the  t wenty -four  hours  ? 

son  of  the 

two  maps.      jn   which  direction  has  the  high-pressure  area  moved? 

Mark  their  courses  on  Figure  35  by  means  of 

a  colored  line  (brown).     Do  the  winds  still  blow  in  the  same  way  (as  in  Fig.  34)  around  the 

high  and  low  pressure  areas?     Is  there  still  the  same  relation  between  pre- 
cipitation and  barometric  pressure  ? Between 

areas  of  pressure  and  temperature?    


• 


By  examining  and  comparing  the  two  maps,  state  what  changes  have  occurred  at  Chicago 
in  (a)  barometric  pressure 


;    (6)  wind  directions 
305 


;    (c)  precipitation 


;  (d)  temperature. 


Make  the  same  comparison  for  New  York. 


For  your  own  home. 


306 


LXVII.  —  STUDY   OF   THE   WEATHER   MAP 

Materials.  For  Each  Student.  —  A  copy  of  a  weather  map  (any  date  will  do). 

For  General  Class  Use.  —  Thermometer.    Barometer.    The  daily  weather  map. 

(The  daily  weather  map  will  be  sent  on  application  from  the  nearest  Weather  Bureau 
.  station,  and  it  should  be  posted  in  a  prominent  place.) 

Purpose.  To  study  the  local  weather  changes  and  note  their  relation  to  high  and  low  pressure  areas. 

The  infor-  Each  student  is  given  a  copy  of  a  weather  map. 

mation  on 

a  weather  what  do  the  dotted  lines  represent  ?     

map. 

Where  is  the  coldest  weather  ?     

The   warmest?      

What  do  the  continuous  lines 

represent?     What  do  the  figures  at  their 

ends  (29.9,  30.2,  etc.)  indicate  ?     Where  is  the 

pressure  highest?      ; 

Where  lowest?     

What  word  is   printed  in  the  anticyclonic  area  or   areas? 

In    the    cyclonic?     What   do   the   arrows   represent? 

In  what  directions  are  the  winds  blowing  in 

the  low-pressure  areas?     


In  the  regions  of  high  pressure  ? 


What  symbols    are  used  to 

represent  clear,  partly  clear,  and  cloudy  sky?      


307 


In  which  of  the  areas,  the  cyclonic  or  the 

anticyclonic,  is  there  the  greatest  extent  of  clear  weather? 


Of  cloudy  weather  ? 


In  what  manner  are  rain  and  snow  recorded  ? 

When,  with  reference  to  the   high  and   low 

pressure  areas,  is  there  most  rain  in  a  given  region  ? 


When  (if  at  all)  is  there  snow  ? 


What  symbol  is  used  for  thunder  storms?     

Do  you  find  any  on  your  map  ?     If  so,  where  do  they  occur  with  reference 

to  the    pressure   conditions?     


What  data  are  printed  in  the  columns  in  the  right-hand  half  of  the  bottom  of  the  map  ? 

From  these  columns  find  out  and  record  the  temperature,  wind  velocity,  and  precipitation  at 
Washington,  D.C.     

At    the   Weather    Bureau 

station  nearest  your  own  home.     

308 


Head  the   printed  matter  on  the  left-hand  part  of  the  bottom  half  of   the   weather  map. 
^|  What  kinds  of  information  are  given  there  ?     .__.      


Study  of  Observe  and  make  a  record  of  the  local  weather  conditions  of  this  day,  as  follows : 

the  local 

weather.        The  temperature.     The  barometric  pressure.     

Direction  of  wind.     Velocity  of  wind  (light,  strong,  etc.)     

Condition  of  sky  (clear,  cloudy,  or  partly  cloudy).     .__ 

Precipitation  (rain,  snow,  or  clear).     Is  the  barometer  low  or  high? 

What  relation,  if  any,  do  you  see  between  the 

pressure  and  the  cloudiness  or  precipitation? 


0 


Is  the  temperature  higher   or   lower   than 

yesterday?     Is  there  any  noticeable  relation  between  this  change  in 

temperature  and  the  pressure  and  wind  direction  ?    


Make  a  prediction,  as  best  you  can, 

for  to-morrow,  —  do  you  expect  it  to  be  warmer  or  colder?     

Rainier   or    clearer?     

Examine  the  weather  map  for   to-day.     Where  is  the  nearest  area  of  high   pressure  ? 

Of  low  pressure?     


In  what  direction,  in  each  case,  from  your  home  ? 
309 


In  which  direction  will  they  probably  move 

by  to-morrow  ?     

Using  the  scale  of  miles  printed  on  the  map,  and  by  comparison  with  yesterday's  map,  find 
out  how  far  each  has  moved  since  yesterday.     


How  many  miles  an  hour  is  that? 

How  far,  then,  may  you  expect  them  to  move 

by   to-morrow?     

What  change  in  your  local  weather  should  these  movements  of  high  and  low  pressure  areas 
bring  about  by  to-morrow  ?    


Now  examine  the   predictions  made  by  the  Weather  Bureau 

and  compare  them  with  your  own  predictions.     


To-morrow  examine  the  weather  map  to  see  how 
nearly  the  predictions  were  verified.     Record  the  results.     


310 


(This  work  may  be  profitably  repeated  for  several  successive  days,  or  until  the  pupil 

thoroughly  understands  the  significance  of  the  weather  map  and  is  able,  from  a  rapid  study 

^k  of  it,  to  see  what  it  shows  as  to  actual  conditions,  and  the  basis  upon  which  predictions  are 

^^  made.     Even  after  the  formal  laboratory  work  on  weather  maps  is  completed,  the  student 

should  examine  the  daily  weather  map,  and  make  his  own  predictions  and^  by  examining  the 

instruments  in  the  school,  note  how  temperature,  wind,  and  precipitation  are   related  to 

pressure.) 

General  From  the  study  of  the  weather  maps,  and  from  the  observation  of  local  weather  condi- 

conclusions.  tions,  answer  the  following  questions :      In  which  direction  do  most  of  the  high  and  low 

pressure  areas  move  ?    


At  about  what  rate?    

When  a  Low  passes  over  your  home,  what  changes  come  (a)  in  pressure, 

(6)  in  temperature,  

(c)  in  wind  direction, (d)  in  wind  velocity, 

(e)  in  cloudiness, 

(/)  in  precipitation  ?    Answer  the  same  questions 

for  the  HiGH-pressure  areas.    

_ (a)  

(6) (c) 

(d)  (e) 

(/)... 

About  how  much  of  the  United  States  do  the  low-pressure  areas  cover  at  any  one  time  ? 


Give  their  greatest  length  and  width  in  miles. 


About  how  far  apart  are  the  Lows  and  Highs  ? 


About  how  often  does  a  Low  pass  over  your  home  ? 


Are  they  always  equally  well  developed  ? 

311 


When  is  there  most  rain,  when  the  low-pressure  area  is  well  developed  or  only 

moderately  developed  ?   { 

During  what  conditions  of  pressure  does  your  coldest  weather  come  ? 


Your  warmest  ? 


Explain  this  in  each  case. 


Cyclonic  storms  develop  in  the  belt  of  prevailing  west  winds.  If  these  winds  should  blow 

every  day  in  your  locality,  would  they  be  dry  or  rainy  winds  ?    _' 

Cold  or  warm  in  winter  ?     Cool  or  hot  in  summer  ? 

Of  what  importance,  therefore  (assuming  that 
you  live  in  the  west-wind  belt),  are  the  cyclonic  storms  to  your  locality :    (a)  because  of  their 


influence  on  temperature  ? 


(6)  because  of  their  influence  on  rainfall  ? 


312 


• 


Materials. 
Purpose. 

Study  of 
isothermal 
chart  of 
the  world 
for  July. 


LX VI II.— ISOTHERMAL  CHARTS  OF  THE  WORLD 

For  Each  Student. —  Colored  pencils. 

To  study  and  interpret  isothermal  charts  of  the  world  for  summer,  winter,  and  the  year. 

Figure  36  is  an  isothermal  chart  of  the  world  for  the  month  of  July.  With  your  colored 
pencils  give  different  colors  to  the  following  parts :  (a)  all  over  80° ;  (b)  from  70°  to  80°  ;  (c) 
50°  to  70° ;  (d)  30°  to  50° ;  (e)  all  below  30°. 

In  what  general  direction  do  most  of  the  isotherms  extend? 
In  which  hemisphere  (northern  or  southern)  do  they  follow  this  direction 


with  greatest  regularity  ?     Explain  the 

difference  between  the  isotherms  of  the  northern  and  southern  hemispheres  in  this  respect. 


Does  the  belt  of  greatest  heat  coincide  with  the  equator?     Draw  a  line  on  the 

map  to  show  the  approximate  position  of  the  belt  of  greatest  heat.     This  will  be  the  heat 
equator  for  July.     Mark  it  so  on  the  map.     Where  does  it  lie  with  reference  to  the  equator  ? 


Are  the  warmest  areas  in  the  northern  or 


southern  hemisphere?    Why 


Are  they  over  the  water  or  over  the  land  ? Why 


Study  of 

isothermal  Figure  37  is  an  isothermal  chart  of  the  world  for  the  month  of  January.     Color  this  map 

the  world  as  follows:    (a)  all  over  80°;    (b)  from  70°  to  80°;    (c)  from  50°  to  70°;    (d)  from  30°  to  50°; 

for  January,  (e)  from  0°  to  30° ;  (/)  from  -  30°  to  0°  ;  (g)  all  below  -  30°. 


313 


Give  two  reasons  why  it  is  so  much  colder  in  the  northern  than  in  the  southern  hemisphere 
in  January.       


Where  are  the  lowest  temperatures  ? 


Why  there  ? 


Where  is  it  warmest  ? 


Why  there  ? 


Draw  in  the  heat  equator  on  this  map.    Explain  its  position. 


Fill  out  this  sentence : 

The  heat  equator  moves  in  summer,  and .    in  winter. 

Comparison  ^n  which  hemisphere  is  there  the  greatest  difference  (called  range)  in  temperature  between 

of  January 

and  July        January  and  July  ?     _ Account  for  this  difference. 

charts.  J  J 


314 


315 


31T 


• 


How  much  is  the  difference,  or  range,  on  the  Arctic  Circle,  on  the  meridian  120°  E.  Long.  ? 

About  how  much  on  the  Antarctic  Circle  on 

the  same  longitude  ?     

On  each  of  the  charts,  follow  the  40°  parallel  of  north  latitude,  and  in  the  table  set  down 
the  temperatures  for  the  places  mentioned.  In  the  lower  columns  insert  the  temperature 
range. 


Month 

Central 
Japan 

Central  Asia 
Long.  80°  E. 

Spain 

Central 

Atlantic 

Long.  40°  W. 

East 
Coast 

U.S. 

Central  U.S. 
Long.  100°  W. 

West 
Coast 
U.S. 

Central 

Pacific 

Long.  160°  W. 

July 

January 

Range 

• 

Account  for  the  high  temperature  range  in  Central  Asia. 


In  central  United  States. 


Contrast  these  temperature  ranges  with  those   in  the  central  Atlantic  and  Pacific  oceans. 


How  do  the  temperature  ranges  on  the  Atlantic  and  Pacific  coasts  of  the  United  States 
compare  ? 


319 


How  do  those  of  the  Atlantic  and  Pacific  coasts  of  Eurasia  compare  ? 


Which  of  the  coasts  of  the  United  States  most  nearly  resembles  eastern  Eurasia  in  tempera- 
ture range  ?     , Western  Eurasia  ? 

How  is  this  to  be  explained  ?     


Study  of  Figure  38  is  an  annual  isothermal  chart  of  the  world ;  that  is,  it  represents  the  average 

isothermal  temperature  for  the  entire  year.     Color  this  map  as  follows :  (a)  all  over  80° ;  (6)  70°  to  80° ; 

woridfor1"5  (c)  50  to  70° ;  ((f)  30°  to  50° ;  (e)  0°  to  30°  ;  (/)  below  0°. 

the  year  ^n   *"ne   map   draw  in   the   heat   equator.     Why  should   it   lie  north  of   the  equator  ? 


Trace  the  isotherm  for  50°  in  the  southern  hemisphere.     What  is  its  direction? 

__._ . Examining  the  ocean  current  map  (Fig.  22),  state  why 

this  isotherm  bends  northward  on  the  west  coast  of  South  America. 


Trace  the  isotherm  for 

50°  in  the  northern  hemisphere.     How  does  it  compare  in  direction  with  the  50°  isotherm  in 


the  southern  hemisphere? 

Account  for  its  northward  bend  in  crossing  the  Atlantic. 


Account  for  its  southward  bend 

320 


321 


on  the  east  coast  of  North  America. 


Account  for  its  northward  bend  in  central  North 

America.     : •___ 


Explain  the  northward  bend  of  isotherms  on   the  west   coasts  of  South  America  and 
Africa.    


The  northward  bend  of  isotherms  between  Iceland  and  Scandinavia. 


_• What  countries  of  west- 
ern Europe  are  crossed  by  the  50°  isotherm?      . 

Where  does  this  isotherm  cross  eastern  United 

States?     


How  do  the  latitudes  of  these  two  places  compare  ? 


What  country  of  Europe  is  in  the  same 

latitude  as  the  part  of  eastern  United  States  that  the  50°  isotherm  crosses  ?    

What  isotherm  crosses  that  part  of  Europe? 

How  do  you  account  for  these  differences 

in  temperature  between  eastern  United  States  and  western  Europe  ?     


323 


How  do  the  isotherms  of  western  Europe  compare  with  those  of  western  United  States  in  the 
same  latitude  ?■ ._•  


Compara-  By  examining  the  isothermal  charts  for  July,  January,  and  the  year,  state,  in  general 

tive  study     terms  and  a  few  sentences,  what  the  summer,  winter,  and  annual  temperatures  are  in  the 
of  isother- 
mal charts. 

Torrid  Zone.     


In  the  North  Temperate  Zone. 


In  the  South  Temperate  Zone. 


In  the  North  Frigid  Zone. 


In  the  South  Frigid  Zone. 


324 


Do  the  boundaries  of  these  zones  seem  to  be  regular,  and  to  follow  exactly  the  circles  of 

latitude?    Where,  for  instance,  do  torrid  conditions  in  summer  extend  into 

the  temperate  zone?     


Where  do  Arctic  conditions  extend  in  winter  into  the  temperate  zone  ? 


Which  isotherm  on  the  July  chart  passes  nearest  your  home  ?     _ 
Name  other  places  in  the  northern  hemisphere  on  the  same  isotherm. 


In  the  southern  hemisphere. 


Answer  the  same  questions  for  the  January  chart. 


For  the  chart  of  the  year. 


325 


Materials. 
Purpose. 


Study  of 
an  isobaric 
chart  of 
the  world. 


LXIX.  —  WINDS   OF  THE   EARTH 

Colored  pencils. 

To  study  the  relation  between  atmospheric  pressure  and  the  planetary  winds;  to  note  the  dis- 
tribution of  these  ivinds;  and  to  consider  their  effects. 

Figure  39  is  an  isobaric  chart  of  the  world  for  the  year.  That  is,  it  shows  the  average 
atmospheric  pressure  for  all  parts  of  the  earth.  With  the  colored  pencils  color  in :  (a)  all 
the  area  which  has  a  pressure  of  over  30.00  inches ;  (b)  the  areas  with  pressure  between  29.90 
and  30.00  inches ;  (c)  the  areas  between  29.80  and  29.90  inches ;  (d)  the  areas  of  less  than 
29.80  inches. 

How  does  the  pressure  in  the  equatorial  belt  compare  with  the  regions  immediately  to 

the  north  and  south  of  it? t Which  way,  then, 

should  the  winds  blow  in  these  regions?     

Make  a  drawing  to  show  the  circulation  of  the 

air  between  the  Tropic  of  Cancer  and  the  Tropic  of  Capricorn.  In  this  drawing  you  should 
show  four  movements  of  the  air:  (1)  along  the  surface;  (2)  a  rising;  (3)  a  flowing  away 
at  the  higher  level ;  and  (4)  a  settling  of  the  air. 


327 


How  does  this  drawing  resemble  that  of  the  circulation  of  air  in  a  room  heated  by  a 
stove  (Fig.  31)  ?     


The  trade  winds  blow  steadily  toward  the  equator  from  both  the  south  and  the  north. 
By  means  of  arrows  indicate  these  winds  on  the  isobaric  chart  (Fig.  39).     To  what  part  of 

the  air  current  in  your  drawing  (Fig.  31)  are  these  winds  equivalent? 


The  belt  of  calms  is  the  area  where  the  warm  air  is  rising.  Indi- 
cate its  position  on  both  the  map  and  the  drawing.  The  anti-trades  are  the  winds  flowing 
away  from  the  equator,  high  above  the  earth's  surface.  Indicate  these  on  your  drawing. 
The  horse  latitudes  are  where  the  air  is  settling.  Mark  the  position  of  the  two  belts  of  horse 
latitudes  on  both  the  map  and  the  drawing.     In  what  direction  would  you  expect  the  winds 

to  blow  on  the  poleward  side  of  the  belts  of  high  pressure?      

These  are  the  two  belts  of  prevailing  westerlies. 

On  Figure  39  find  several  places  where  the  pressure  is  over  30.10  inches.     Which  way 

must  the  air  be  moving  in  these  areas  of  high  pressure  ? 

Find  two  areas  in  the  .northern  hemisphere  where  the  pressure  is  as  low  as  29.70  inches. 

How  must  the  winds  be  blowing  in  these  regions  ?     


The  wind  Figure  40  shows  the  prevailing  winds  of  the  earth  in  the  month  of  January.  You  wi*l 
belts.  note  that  the  wind  directions  in  the  regular  wind  belts  do  not  exactly  agree  with  those  you 
have  drawn  in  Figure  39.  The  winds  have  been  deflected  from  true  north  and  south  directions 
by  the  influence  of  the  earth's  rotation.  On  Figure  40  place  the  following  names  in  their 
proper  places:  northern  prevailing  westerlies ;  southern  prevailing  westerlies ;  belt  of  north- 
ern horse  latitudes;  belt  of  southern  horse  latitudes;  belt  of  northeast  trades;  belt  of  south- 
east trades;  belt  of  calms,  or  doldrums.     In  which  two  belts  is  the  air  settling?     


•     In  which 

belt  is  the  air  rising?      


On  page  314  you  learned  that  the  heat  equator  moves  north  in  summer  and  south  in  win- 
ter.    Since  the  trade  winds  represent  cooler  air  flowing  toward  this  heated  belt,  what  change 

in  their  position  must  occur  with  the  changes  in  season?     j 


328 


40°      East         from       80°       Greenwich  120° 


Fig.  39, 


West        from      40°       Greenwich  0°        Longitude  40°      East         from      80         Greenwich  120  J 


Fig.  40. 


329 


Deflection  Currents  of  air  and  water  on  the  earth  are  turned  by  the  influence  of  the  earth's  rotation 

of  winds  by  toward  the  right  in  the  northern  hemisphere,  and  toward  the  left  in  the  southern  hemisphere 

the  earth's    (Text-book,  p.  258);  that  is,  if  you  stand  so  that  a  current  strikes  your  back,  the  current  will 

be  deflected  towards  your  right  in  the  northern  hemisphere.     Apply  this  to  explain  why  the 

trade  winds  blow  from  the  northeast  and  southeast,  instead  of  from  due  north  and  south. 


What  compass  direction  does  the  influence  of  rotation  cause  winds  to  have  in  the  northern 

hemisphere  when  blowing  from  the  south?     

What  direction  in  the  southern  hemisphere  when  blowing  from  the  north  ? 

How  does  this  apply  in  explaining  the  direction  of  the  pre- 
vailing westerlies?   


Winds  in  What  is  the  direction  of  the  winds  in  Eurasia :  (a)  in  the  northern  part  ? 

areas  of  low 

and  high 

pressure.       >  (&)  m  the  eastern  part  ?     


(c)  in  the  southern  part?    Why  should  winter 

winds  blow  outward  from  the  cold  interior  of  a  continent?    


__1 On  the  map  of  the  isobars  (Fig.  39) 

there  are  three  areas  of  high  pressure  over  the  ocean  in  the  southern  horse  latitude  belt,  and 
two  in  the  northern  horse  latitude  belt.     Locate  these  five  areas  on  Figure  40  and  state  how 

the  winds  blow  in  such  areas.    


# 


Locate  the  two  areas  of  low  pressure  (in  the  North  Atlantic 


and  North  Pacific)  and  state  how  the  winds  blow  there. 

331 


Winds  on  Is  the  temperature  of  water  more  or  less  uniform  than  that  of  land?  

water  and 

land-  Differences  in  temperature  give  rise  to  differences  in  air  pressure, 

and  these  to  winds.     Where,  then,  should  the  winds  have  a  more  regular  direction,  on  land  or 

on  water?     Examine  the  map  to  see  if  the 

trade  winds  have  a  more  constant  direction  on  land  or  on  water.     

How  about  the  belt  of  northern  prevailing  westerlies  ?    


The  southern  belt 


of  prevailing  westerlies  ? 


Why  do  the  latter  winds  blow  more  regularly  than  those  of  the 


northern  hemisphere  ? 


Windward 
and  lee- 
ward 
coasts. 


On  which  coasts  (east-facing  or  west-facing)  do  the  trade  winds  blow  from  the  sea? 

On  which  from  the  land?   

On  which  coasts  do  the  prevailing  westerlies  blow  from  the 

sea? What  effect  must  this  have  on  the 

temperature  of  the  land  that  they  reach  ?     


land?     

temperature  of  these  coasts  in  summer  ? 


On  which  coasts  do  the  westerlies  blow  from  the 
.__     What  effect  must  this  have  on  the 


332 


In  winter  ? 


Which  of  the  coasts  (east  or  west) 

in  the  westerly  belts  must  therefore  have  the  more  equable  climate?     


333 


♦ 


LXX.— RAINFALL   OF   THE   UNITED   STATES 

Materials.  For  Each  Student.  —  Colored  pencils.     Ruler. 

For  General  Class  Use.  —  A  rain  gauge.     (A  tinsmith  can  make  a  fairly  satisfactory  rain 
gauge.     See  Text-book,  p.  424.) 

Purpose.  To  study  the  distribution  of  rainfall  in  the  United  States,  and  to  discover  the  reasons  for  the 

differences  in  amount. 

Observing  For  two  weeks  keep  a  record  of  the  amount  of  rainfall,  measuring  it  after  each  rain. 

amount  of     Measure  the  depth  of  the  water  in  the  tube  with  a  ruler,  remembering  that  this  depth  is  ten 

rainfall.        times  the  actual  rainfall.     Why  is  it  advisable  to  so  construct  the  rain  guage  that  the  rain 

from  an  area  of  ten   square  inches  is  collected   instead  of  from   only  one  square  inch? 


• 


What  is  meant  when  one  says  "  an  inch  of  rain  has  fallen  "  ? 


Is  an  inch  of   rain  a  light  or 

heavy  rainfall?     What  is  meant  by  saying 

"the  annual  rainfall  is  100  inches"?     . 


1 What  is  the  rainfall  of  your  own  region  (Fig.  41)? 

Has  a  region  with  100  inches  of  rainfall  a 

dry  or  a  rainy  climate? !_._ 

Fill  the  cylinder  of  the  rain  gauge  with  snow  to  a  depth  of  ten  inches  (but  do  not  pack 
it  tightly),  and   allow  the  snow  to  melt.     How  much  water  gathers  in  the  bottom  of-  the 

cylinder?     What  do  you  conclude   therefore  as  to  the  amount  of 

snow  that  represents  an  inch  of  rain?     


335 


Rainfall  of  On  the  map  of  the  United  States  (Fig.  41)  the  lines  indicate  the  amount  of  rainfall  in 

the  United    inches.     Color  in  (with  green  pencil)  the  areas  with  a  rainfall  of  over  60  inches.     In  what 
States. 

two  parts  of  the  country  is  there  the  heaviest  rainfall  ?     


By  examining  the  map   showing  the 
winds    of    the    earth    (Fig.    40)    account    for    these    two    areas    of    heavy    precipitation. 


Color  in  (with  blue   pencil)  the  areas  with  a  rainfall  of   be- 
tween 50  and  60  inches.     A  rainfall  of  50  inches  or  more  is  heavier  rainfall  than  is  common. 

What  parts  of  our  country  have  such  a  condition  of  rainfall  ?     


Color  in  (with  brown  pencil)  those  sections  with  a  rainfall  of  less  than  10  inches.  Such 
a  rainfall  is  altogether  too  little  for  agriculture,  and  deserts  commonly  exist  where  there  is 
such  light  rainfall.     What  states  and  parts  of  states,  therefore,  have  a  desert  condition  of 

rainfall  ?     


In  which  of  the  wind  belts  are  these  desert  regions  located  ? 


What  explanation  can  you  give 

for  these  desert  conditions  ?     


336 


337 


f 


I 


t 


♦ 


Color  in  (with  yellow  pencil)  the  sections  with  a  rainfall  of  from  10  to  20  inches.  In 
general,  a  rainfall  of  less  than  20  inches  is  too  little  for  agriculture ;  and  the  country  included 
in  the  belt  with  rainfall  between  10  and  20  inches  may  be  called  the  arid  country.     What 

states,  or  parts  of  states,  are  included  in  this  arid  belt?     


What  explanation  can  you  offer 

for  the  fact  that  the  arid  lands  are  mainly  in  the  interior  of  the  country  ?     


In   the    arid    belt 

you  will  note  on  the  map  that  there  are  small  areas  with  a  heavier  rainfall.     What  is  the 

explanation  of  these? 


Why  is  there  such  an  abrupt  change  from  heavy  rainfall  in  western 

Washington  to  light  rainfall  in  eastern  Washington  ? 


Fill   out   the   following   sentence:    On 

the  windward  side  of  mountains  the  rainfall  is     ;  on  the  leeward  side 

the  rainfall  is     

Why  is  evaporation  greater  in  the  southern  than  in  the  northern  part  of  the  arid  belt  ? 


339 


How  does  this  help  to  explain  the  fact  that  in  some  parts  of  the  north,  as  in  eastern  Washington 
and  eastern  Dakota,  there  is  extensive  wheat  raising,  although  the  rainfall  is  less  than  20 

inches  ?      


Color  in  (with  red  pencil,  in  parallel  ruled  lines)  the  areas  with  a  rainfall  of  from  20  to  30 
inches.     What  states  are  partly  included  in  this  belt  ?     


Account  for  the  fact  that  in  Texas 

the  western  portion  of  this  area  has  too  little  rainfall  for  agriculture.      


Color  in   (with   blue 

ruling)  the  areas  with  a  rainfall  between  30  and  40  inches ;  and  the  areas  (with  green  ruling) 
between  40  and  50  inches.      About  what  proportion  of  the  United  States  has  rainfall  enough 

for  agriculture  (20  inches  or  over)?     ' In  what 

parts  of  the  country  is  this  condition  general  ?    


for  agriculture  in  the  arid  and  desert  sections  ? 


What  means  are  adopted  to  supply  moisture 


State  how  the  rainfall  varies  from  the  mouth  of  the  Mississippi  to  northern  Minnesota. 


340 


From  Virginia  to  southern  California. 


# 


From  the  coast  of  Washington  to  the  coast  of  Maine. 


Following  along  several  lines  from  the  coast  to  the  interior,  what  do  you  discover  as  to  the 

general  change  in  amount  of  rainfall?     Fill 

out  the  following  sentence:  In  general,  the  amount  of  rainfall  from 

coast  to  interior.     Account  for  this  fact.     


341 


t 


* 


LXXI.  —  RAINFALL  OF  THE  EARTH 

Materials  For  Each  Student.  —  Colored  pencils. 

Purpose.  To  study  and  understand  the  cause  for  the  distribution  of  rainfall  over  the  earth. 

Belts  of  Figure  42  is  a  blank  map  of  the  world  with  the  rainfall  of  the  continents  indicated  by  a 

heavy  rain-  series  of  lines.     By  reference  to  the  Text-book  (Fig.  444),  secure  data  for  filling  in,  with  the 
fall.  green  pencil,  the  areas  which  have  heavy  rainfall.     In  which  zone  do  most  of  these  areas  lie  ? 

By  examining  the  map  of  winds  of  the  earth 

(Fig.  40),  determine  in  which  of  the  wind  belts  the  largest  areas  of  heavy  rainfall  lie? 


How  do  you  account  for  this  fact  ? 


There  is  heavy  rainfall 

also  in  some  small  sections  of  the  temperate  zones.     On  which  coasts  of  the  continents  are  these 

located?     In  what  wind  belts  ?      

Account  for  these  areas  of  heavy  rainfall.     


Desert  Color  in  (with  brown  pencil)  the  areas  which  have  desert  conditions.     In  which  zones  are 

areas. 

these  located?     !__ 


Why  should  there  be  arid  conditions  in  the  horse  latitude  belts  ? 


343 


Which 

coasts  (east  or  west  facing)  have  desert  conditions  in  the  trade  wind  belts  ?     _"" 

Why  is  there  heavy  rainfall  on  the  opposite  coasts  in  these 
belts?      •_.. 


Till  in  this  sentence :    Windward  coasts  in  the  trade  wind  belts  have 


rainfall;  leeward  coasts  have  rainfall.     Cuba  and  Porto  Rico  lie  in 

the  path  of  the  northeast  trade  winds.     What  must  be  the  condition  of  rainfall  on  the  north- 

east  side?     On  the  southwest  side  ?    

Account  for  the  arid  regions  in  the  west  wind  belts  of  North  America  and  South  America. 


Which  continents  have  the  largest  area  of  desert  land  ? 


How  do  you  account  for  this  in  each 

case? 


Regions  of             Color   in   (with  yellow  pencil)   the   regions   of   light   rainfall.     What  portions  of  the 
light  rain- 
fall, northern  continents  are  included?     


Why  should  there  be  less  rainfall  in  the  cold  north  than 

in  the  warm  south?     

344 


a 


345 


t 


t 


9 


Why  are  regions  of  light  rainfall  extensive  in  the  continent  interiors  f 


Would  these  regions  of  light  rainfall  be  better  suited  for  grazing  or  for  agriculture  ? 
Why  would  this  be  less  true  in  the  cool  north  ? 


As  the  belt  of  calms  shifts  northward  in  summer  and  southward  in  winter,  how  would 
the  rainfall  vary  with  the  season  in  that  part  of  Africa  that   lies  south  of  the  Desert  of 


Sahara  ?     (Text-book,  p.  283.) 


How  would  the  rainfall   vary  with  the  season   in    the  southern 
part  of  Africa? 


At  what  season  would  agriculture  be  possible  in  each  of  these  two  regions  ? 

Why  are  these  regions  (the  savannas)  grass 
lands  and  not  forest-covered  lands  ?      


Regions  of             Color  in  the  remainder  of  the  map  (with  blue  pencil)  to  show  the  areas  of  moderate  rain- 
moderate 
rainfall.        fa|]      What  parts  of  North  America  are  included  ?     

347 


Of  Eurasia? 


Europe,  eastern  United 

States,  and  southeastern  Asia  are  the  most  densely  settled  parts  of  the  earth.     What  is  the 


condition  of  rainfall  in  each  of  these  sections  ? 


Why    are    desert  countries    sparsely 

settled?     


Why  are  the  warm  regions  of  heavy  rainfall  also  unsuited  to  dense  settlement  ? 


What  reasons  can  you  give  for  the  fact  that  the  most  densely  settled  parts  of  the  earth  are 
mainly  located  in  those  parts  of  the  temperate  zone  in  which  there  is   moderate  rainfall  ? 


Compar-  How  does  North  America  compare  with  other  continents  in  amount  of  desert  ? 

ison  of 

North 

America 

with  other 

continents.     

348 


In  extent  of  country  having  heavy  rainfall  ? 


In  extent  of  country  having  moderate  rainfall  ? 


In  which  of  these  respects  is  North  America  favored  as  compared  with  other  continents  ? 

Write  a  brief  statement  as  to  the  advantages  that  North  America  has  as   to  rainfall  and 
temperature  as  compared  with  (a)  Eurasia;    (6)  South  America;  (c)  Africa;  (d)  Australia- 


349 


c 


LXXIL  —  LIFE   ZONES   ON   THE   EARTH 

Purpose.  To  understand  the  relation  between  climate  and  the  plant  zones  of  the  earth;  and  the  chief 

reasons  for  the  distribution  of  animal  life  on  the  earth. 


Fig.  43. —  Zones  of  Plant  Life  in  the  United  States  as  influenced  by  Temperature. 

Plant  zones  Figure  43  shows  the  different  zones  of  plant  life  in  the  United  States  as  influenced  by 

of  the  the  temperature.     In  what  three   sections  of  the   country  are  tropical   conditions  found  ? 

United  J  r 

States. 


Explain  the  presence  of  tropical  conditions  in  each  of  these  three  places. 


J 


351 


^    V 


B 

I 


"2 


TT' 


352 


Where  are  cold  north-temperate  conditions  found?     

f  Explain  the  presence  of  cold  climate  plants  so  far  to  the  south  in  western  United  States. 

In  what  portions  of  the  country  are  warm  temperate  plants  found?     


Cool  temperate  plants  ? 


Distribu-  Trace  the  northern  limit  of  trees  (Fig.  44).     Why  cannot  trees  grow  north  of  this  line  ? 
tion  of 

Plantsin       . To  the  north  of  the  tree  line  is  the  tundra 

e  wor    '  region.     What  countries  of  Eurasia  and  North  America  are  partly  within  the  tundra  belt  ? 


Why  is  there  so  little  tundra  in  the  southern  hemisphere  ? 


Trace  the  northern  and  southern  limits  of  palms.     What  kind  of  climate  do  they  require  ? 

What  countries  of  Europe  and  North  America 

are  included  in  the  belt  of  palms?     


Why  does  the  limit  of  palms  extend  so  much  farther 

north  in  Europe  than  in  America?     


What  two  continents  are  almost  wholly  in  the  belt  of  palm  growth  ? 


In  which  continents  are  the  tropical  forests  most  extensive  ? 


353 


In  what  wind  belts  (Fig.  40)? 

What  are  the  temperature  and  rainfall  conditions  in  the  tropical  forest  belt  ? 


Make  a  list  of  the  tropical  trees  of  which  you  know  the  names. 


Through  what  countries  does 

the  belt  of  m  ost  extensive  forest  in  the  temperate  zone  extend  ?    


What    are    the    temperature 

and  rainfall  conditions  there?    

Make  a  list  of  some  trees  that  grow  in  the  cool  temperate 
forest.    

In  which,  fhe  temperate  or  tropical  forest  belt,  does  vegetation   grow   most   luxuriantly? 

Through  which  of  these  forest  belts  would  it 

be  more  difficult  for  an  explorer  to  pass  ?    

Why  should  so  much  forest  be  left  in  the  more 
northerly  countries,  while  it  has  been  stripped  off  in  the  regions  immediately  to  the  south  ? 


Explain   the   long,  narrow  strips    of    forest    in  the    belt   south   of    the  northern    forests. 


9 


9 


354 


3 


ft 


In  what  zones  are  the  principal  agricultural  belts  located  ? 


What  leading  countries  in 

the  northern  hemisphere  are  included?     


What    countries   in   the    southern   hemisphere  ? 


What  are  the  rainfall  conditions  in  these  belts  ? 


..     If  the  land  were  not  needed  for  agricul- 


ture, would  forests  grow  in  these  belts?     Trace  the  northern  limit  of 

grain.     What  countries  of  the  northern  hemisphere  are  partly  to  the  north  of  this  line  ? 


What  countries  of  the  southern  hemisphere   extend   beyond  the  limit   of   grain   growth  ? 

In  which  hemisphere,  northern  or  southern,  is  most  agricultural  land  found  in  the  temperate 

zone?    

Locate  the  chief  deserts   and  tell  in  which  part  of  each  continent  they  are   found. 


Which  continent   has   most    desert?    Which 

continent  least?     How  does  North  America 

rank  in  amount  of  desert?     


Why  will  forests  not  grow  in  deserts  ?     .. 
355 


In  what  zones  are  the  largest  deserts  located?     

In  what  rainfall 

belts?     


Where  are  the  principal  grazing  lands  located  ? 


What  are  the  rainfall  conditions  in 

such  regions  ?     WThy  are  the  savannas  of  the 

torrid  zone  arid  in  one  season  ?     


Why  are  there  great  areas  of  grazing  land  in  the  interiors 

of  continents  ?    

Why  do  forests  not  grow  in  these  regions  ?     


Are  the  grazing  lands  sparsely 

or   densely  settled?      How  must   they  com- 
pare with  the  agricultural  lands  in  respect  to  density  of  population?     


With    the   deserts? 


Why  are  the  tropical  forests  not  densely  settled  ? 


Distribu-  Figure  45  shows  the  three  realms  of  animal  life,  and  some  of  the  main  subdivisions.     In 

tion  of  each  0f  these  divisions  the  animals  differ  very  much.     From  this  map,  what  should  vou  iudee 

animal  life.  r  j       j      t> 

was  the  chief  barrier  to  the  spread  of  types  of  animals  that  live  on  the  land  ? 

356 


} 


ANTARCTIC  CIRCLE 


100°    Longitude  WeBt     60"     from  Greenwich      20s 


20°     Longitude  East       60°    from  Greenwich      100° 


Fig.  45.  —  Map  showing  Three  Realms  of  Animal  Life  and  Main  Subdivisions. 

Do  deserts  also  serve  as  a  barrier?     

mountain  ranges  ?     Do  differences  in  temperature  ?     

Why  should  South  American  animals  differ  so  greatly  from  those  of  Africa  ? 


Do 


What  bar- 
rier would  serve  to  check  the  spread  of  life  to  Australia  ?      

What  barrier  partly  cuts  off  the  Oriental  Region  from  the  Northern  Realm  ? 

What  barrier  tends  to  prevent  the  spread  of 

animal  life  from  the  Northern  Realm  into  the  Ethiopian  Region?     

Is  such  a  barrier  as  effective  as  that  between  Africa  and  South  America? 

357 


How  may  differences  in  climate  help  to  account  for  the  failure  of 

animals  of  North  and  South  America  to  migrate  more  freely  ?     


What  one  condition  affecting  animal  life  is  practically  the  same  throughout  the  extensive 
Northern  Realm  ?    

How  can  you  explain  the  fact  that  the  animal  life  throughout  this  great 

realm  is  so  nearly  alike?     


What  would  be  the  effect  of  former  greater  elevations  partly  or 

wholly  closing  up  the  water  areas  between  the  continents  ?    


Australian  animals  are  wholly 

different  from  those  of  southern  Asia.     What  does  this  fact  indicate  as  to  the  probability  of 

former  connection  between  these  two  lands  ?     


# 


t 


358 


J 


LXXIII.  —  MAGNETISM 

Materials.  For  Each  Student.  —  Two  small  needles. 

For  General  Class  Use.  —  Several  small  bar  magnets  (preferably  one  for  each  student).     One  or 
more  magnetic  compasses. 

Purpose.  To  study  the  properties  of  a  magnet,  the  magnetism  of  the  earth,  and  the  use  of  a  compass. 

The  attrac-  Let  each  student  take  one  of  the  magnets  and  place  it  near  his  needle.     What  happens? 

tion  of  a 

magnet'        Place  one  end  of  the  magnet  near  the  needle 

point.     Now  place  the  other  end  near  the  needle  point.     Repeat  this  at  the  other  end  of  the 

needle.    What  happens  in  each  case  ?     


Try  the  magnet  on  objects  other  than  iron  (such  as 

glass,  a  penny,  a  nickel,  a  dime,  etc.)     What  is  the  result?     

What  can  you  say  about  the 

attraction  of  the  magnet  ? 


Complete  this  sentence :     There  is  some  force  in  the    _  _ 

which  draws  the to  it.    Of  what  metal  is  the  needle  made  ? 


Does  the  magnet  attract  other  iron  objects  (such  as  a  knife,  nails,  etc.)?     

Magnetiz-      Rub  one  of  the  needles  over  the  magnet  several  times.     Place  this  needle  near  the  other  one. 
inga 

needle.  What  happens?     . 

Now  place  one  end  of  the  magnet  near  the  point  of  the  needle 

that  you  have  rubbed  on  the  magnet.     What  happens  ? 

Try  the  other  end  of  the  magnet.     What  happens?      

359 


Go  through  the  same  procedure  with  the  eye  of  the  needle.     What  is  the  difference  in  the  be- 
havior of  this  needle  as  compared  to  the  one  that  was  not  rubbed  on  the  magnet  ?     _ 


The  two  ends  of  the  magnet  are  called  its  poles.     Since  the  needle  is  now  a  magnet,  what  may 

its  two  ends  be  called  ? Like  poles  of  a  magnet  repel  each  other ; 

and  unlike  poles  attract  each  other.     From  this  principle  determine  the  like  poles  in  the  mag- 
net and  the  needle.     Find  which  end  of  the  magnet  will  repel  the  north  end  of  the  needle  in 

the  compass.     

Suggestion  Take  the  magnetized  needle  home.     Cut  off  a  thin  slice  from  a  small  cork  and  thrust  the  needle  through 

for  home        the  thin  edge  and  parallel  to  the  flat  surface.     Place  this  in  a  dish  of  water  and  the  cork  will  float  the  needle, 
work. 


Which  way  does  the  needle  point. 


Change  its  position 


and  note  if  it  returns  to  the  same  position  as  before  ?      Repeat  this  experiment 

several  times.     If  you  could  get  the  same  result  in  all  parts  of  the  world,  what  useful  purpose  would  such  a 


floating  needle  serve  ? 


The  com- 
pass. 


How  can  you  prove  that  the  needle  of  the  compass  is  not  an  ordinary  piece  of  steel  ? 

Does  it  behave  like  the  ordinary  needle,  or  the  magnetized  needle,  when  the  different  poles  of 
the  magnet  are  brought  up  to  it  ?     


Earth's 
magnetism. 


What  does  this  prove 


In  what  directions  do  the  two  ends  of  the  needle  of  the  compass  point?     

What  makes  the  needle  always  come  to  rest  in  that  position  ? 


On  a  large  globe  or  a  map  of  North  America  find  Boothia  Land  where  the  north  magnetic  pole  is 

situated.     What  is  its  location  with  reference  to  the  north  pole  of  the  earth  ?     

360 


O 


In  which  of  your  previous  experiments  have  you  determined  the 

true  north-south  line  ?      Does  the  compass 

needle  point  toward  the  north  pole  or  the  north  magnetic  pole?     

What  is  the  meaning  of  "true  north " ?      


Of   "magnetic   north"? 


With  the  compass  find  how  many  degrees  difference  there  is  between  true  and  magnetic  north 

in  your  locality.     .. 

Isogonic  Figure  560  in  the  Text-book  is  an  Isogonic  Map.     What  does  it  illustrate  ?     

map. 


Find  the 

isogonic  line  that  runs  nearest  your  home  and  draw  it  on  the  map  (Fig.  46).     How  much  is  the 

declination?     Is  it  east  or  west  declination? 

Knowing  the   declination,   what  correction  to   a  compass   reading 

would  you  have  to  make  to  get  true  north  ?      

2 Draw  on  the  map  the  isogonic  line  that  runs 

nearest  New   York   City.     What   is  the   amount   and   direction   of  the   declination  there  ? 

Do  the  same  for  Columbia,  S.C.     

For  Augusta,  Me.     

For  San  Francisco.     In  what  part  of 

the  United  States  is  there  greatest  east  declination  ?     

Greatest  west  declination  ?     

Use  of  the  Of  what  use  is  the  compass  ?      

compass. 


361 


Fig.  46. —  Blank  Chart  fob  drawing  Isogonic  Links. 
Why  is  it  more  useful  to  sailors  than  to  any  other  class 


of  men  ? 


What  is  the  significance  of  the  fact  that  the  use  of  the  compass  was  discovered  just  before  the 
time  of  Columbus  ?      


362 


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Professor  of  Dynamic  Geology  and  Physical  Geography  at  Cornell  University 


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